Changes in Equity (Details) - USD ($) $ / shares in Units, $ in Thousands |
3 Months Ended | 6 Months Ended | ||||
|---|---|---|---|---|---|---|
Jun. 30, 2023 |
Mar. 31, 2023 |
Jun. 30, 2022 |
Mar. 31, 2022 |
Jun. 30, 2023 |
Jun. 30, 2022 |
|
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Beginning balance | $ 829,051 | $ 772,887 | $ 727,876 | $ 651,711 | $ 772,887 | $ 651,711 |
| Beginning balance, treasury stock (in shares) | Ìý | 60,477 | Ìý | Ìý | 60,477 | Ìý |
| Net income | 100,393 | $ 86,568 | 118,894 | 97,900 | $ 186,961 | 216,794 |
| Share-based compensation, net of forfeitures | 2,806 | 2,370 | 1,811 | 1,481 | Ìý | Ìý |
| Repurchases of common stock | (19,708) | (6,749) | (25,534) | Ìý | Ìý | Ìý |
| Shares exchanged for tax withholdings | Ìý | (939) | Ìý | Ìý | Ìý | Ìý |
| Periodic pension costs, net of income taxes | (26) | (25) | 8 | 8 | (51) | 16 |
| Ending balance | $ 887,550 | 829,051 | $ 645,281 | 727,876 | $ 887,550 | $ 645,281 |
| Ending balance, treasury stock (in shares) | 77,011 | Ìý | Ìý | Ìý | 77,011 | Ìý |
| Cash dividends per share of common stock (in USD per share) | $ 3.25 | Ìý | $ 23.00 | Ìý | $ 6.50 | $ 26.00 |
| Excise taxes collected | $ 165 | 67 | Ìý | Ìý | Ìý | Ìý |
| Periodic pension costs (benefit), net of income taxes | $ (8) | $ (6) | $ 2 | $ 2 | $ (14) | $ 4 |
| Common Stock | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Beginning balance (in shares) | 7,693,320 | 7,695,679 | 7,745,290 | 7,744,695 | 7,695,679 | 7,744,695 |
| Beginning balance | $ 78 | $ 78 | $ 78 | $ 78 | $ 78 | $ 78 |
| Share-based compensation, net of forfeitures (in shares) | Ìý | 1,756 | 104 | 595 | Ìý | Ìý |
| Repurchases of common stock (in shares) | (14,175) | (3,627) | (17,478) | Ìý | Ìý | Ìý |
| Shares exchanged for tax withholdings (in shares) | Ìý | (488) | Ìý | Ìý | Ìý | Ìý |
| Ending balance (in shares) | 7,679,145 | 7,693,320 | 7,727,916 | 7,745,290 | 7,679,145 | 7,727,916 |
| Ending balance | $ 78 | $ 78 | $ 78 | $ 78 | $ 78 | $ 78 |
| Treasury Stock | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Beginning balance | $ (108,794) | $ (104,139) | $ (14,617) | $ (15,417) | $ (104,139) | $ (15,417) |
| Beginning balance, treasury stock (in shares) | 62,836 | 60,477 | 10,866 | 11,461 | 60,477 | 11,461 |
| Share-based compensation, forfeitures (in shares) | Ìý | (1,756) | (104) | (595) | Ìý | Ìý |
| Share-based compensation, net of forfeitures | Ìý | $ 3,033 | $ 140 | $ 800 | Ìý | Ìý |
| Repurchases of common stock (in shares) | 14,175 | 3,627 | 17,478 | Ìý | Ìý | Ìý |
| Repurchases of common stock | $ (19,708) | $ (6,749) | $ (25,534) | Ìý | Ìý | Ìý |
| Shares exchanged for tax withholdings (in shares) | Ìý | 488 | Ìý | Ìý | Ìý | Ìý |
| Shares exchanged for tax withholdings | Ìý | $ (939) | Ìý | Ìý | Ìý | Ìý |
| Ending balance | $ (128,502) | $ (108,794) | $ (40,011) | $ (14,617) | $ (128,502) | $ (40,011) |
| Ending balance, treasury stock (in shares) | 77,011 | 62,836 | 28,240 | 10,866 | 77,011 | 28,240 |
| Additional Paid-in Capital | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Beginning balance | $ 7,733 | $ 8,293 | $ 1,505 | $ 28 | $ 8,293 | $ 28 |
| Share-based compensation, net of forfeitures | 2,849 | (560) | 1,851 | 1,477 | Ìý | Ìý |
| Ending balance | 10,582 | 7,733 | 3,356 | 1,505 | 10,582 | 3,356 |
| Accum. Other Comp. Income (Loss) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Beginning balance | 2,491 | 2,516 | (999) | (1,007) | 2,516 | (1,007) |
| Periodic pension costs, net of income taxes | (26) | (25) | 8 | 8 | Ìý | Ìý |
| Ending balance | 2,465 | 2,491 | (991) | (999) | 2,465 | (991) |
| Retained Earnings | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Beginning balance | 927,543 | 866,139 | 741,909 | 668,029 | 866,139 | 668,029 |
| Net income | 100,393 | 86,568 | 118,894 | 97,900 | Ìý | Ìý |
| Share-based compensation, net of forfeitures | (43) | (103) | (180) | (796) | Ìý | Ìý |
| Ending balance | 1,002,927 | 927,543 | 682,849 | 741,909 | $ 1,002,927 | $ 682,849 |
| Dividend Paid | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Dividends paid | $ (24,966) | $ (25,061) | $ (23,188) | $ (23,224) | Ìý | Ìý |
| Cash dividends per share of common stock (in USD per share) | $ 3.25 | $ 3.25 | $ 3.00 | $ 3.00 | Ìý | Ìý |
| Dividend Paid | Retained Earnings | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Dividends paid | $ (24,966) | $ (25,061) | $ (23,188) | $ (23,224) | Ìý | Ìý |
| Special Dividend Paid | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Special dividends paid | Ìý | Ìý | $ (154,586) | Ìý | Ìý | Ìý |
| Cash dividends per share of common stock (in USD per share) | Ìý | Ìý | $ 20.00 | Ìý | Ìý | Ìý |
| Special Dividend Paid | Retained Earnings | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Special dividends paid | Ìý | Ìý | $ (154,586) | Ìý | Ìý | Ìý |
| X | ||||||||||
- Definition Amount of paid and unpaid special cash dividends declared for classes of stock, for example, but not limited to, common and preferred. No definition available.
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- Definition Amount of decrease to equity for grantee's tax withholding obligation for award under share-based payment arrangement. No definition available.
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- Definition Amount of increase to additional paid-in capital (APIC) for recognition of cost for award under share-based payment arrangement. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Aggregate dividends paid during the period for each share of common stock outstanding. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount of paid and unpaid cash dividends declared for classes of stock, for example, but not limited to, common and preferred. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition The excise taxes collected by a public utility and reported in revenues if the amount of excise taxes is equal to 1 percent or more of such total. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. No definition available.
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- Definition The portion of profit or loss for the period, net of income taxes, which is attributable to the parent. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount after tax and reclassification adjustments of other comprehensive income (loss). Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount of tax expense (benefit) allocated to other comprehensive income (loss) attributable to parent entity. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Number of shares issued which are neither cancelled nor held in the treasury. No definition available.
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- Definition Number of shares used to settle grantee's tax withholding obligation for award under share-based payment arrangement. No definition available.
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- Definition Number, after forfeiture, of shares or units issued under share-based payment arrangement. Excludes shares or units issued under employee stock ownership plan (ESOP). Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Number of shares (or other type of equity) forfeited during the period. No definition available.
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- Definition Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Number of previously issued common shares repurchased by the issuing entity and held in treasury. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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