Summary of Significant Accounting Policies - Adoption of ASU 2014-09 (Details) - USD ($) $ / shares in Units, $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2018 |
Sep. 30, 2018 |
Jun. 30, 2018 |
Mar. 31, 2018 |
Dec. 31, 2017 |
Sep. 30, 2017 |
Jun. 30, 2017 |
Mar. 31, 2017 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|
Consolidated Statements of Income: | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Revenue | $ 93,201 | $ 73,168 | $ 73,844 | $ 60,007 | $ 39,957 | $ 51,977 | $ 32,293 | $ 30,407 | $ 300,220 | $ 154,634 | $ 66,109 |
Taxes, other than income taxes | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 265 | 167 |
Income taxes - deferred | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 14,814 | 966 | (1,420) |
Net income | $ 62,680 | $ 50,762 | $ 52,503 | $ 43,791 | $ 24,620 | $ 33,002 | $ 20,350 | $ 19,259 | $ 209,736 | $ 97,231 | $ 42,275 |
Net income per Sub-share Certificate (in dollars per share) | $ 8.06 | $ 6.52 | $ 6.73 | $ 5.60 | $ 3.14 | $ 4.20 | $ 2.58 | $ 2.43 | $ 26.93 | $ 12.38 | $ 5.29 |
Assets: | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Accrued receivables | $ 48,750 | Ìý | Ìý | Ìý | $ 17,773 | Ìý | Ìý | Ìý | $ 48,750 | $ 17,773 | Ìý |
Deferred tax liability | Ìý | Ìý | Ìý | Ìý | (114) | Ìý | Ìý | Ìý | Ìý | (114) | Ìý |
Liabilities and Capital: | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Unearned revenue | 13,369 | Ìý | Ìý | Ìý | 8,364 | Ìý | Ìý | Ìý | 13,369 | 8,364 | Ìý |
Other taxes payable | Ìý | Ìý | Ìý | Ìý | 0 | Ìý | Ìý | Ìý | Ìý | 0 | Ìý |
Net proceeds from all sources | $ 245,769 | Ìý | Ìý | Ìý | 105,902 | Ìý | Ìý | Ìý | $ 245,769 | 105,902 | Ìý |
As reported | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Consolidated Statements of Income: | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Revenue | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 132,329 | $ 59,911 |
Taxes, other than income taxes | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 3,161 | 1,779 |
Income taxes - deferred | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | (3,365) | (4,194) |
Net income | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 76,361 | $ 37,240 |
Net income per Sub-share Certificate (in dollars per share) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 9.72 | $ 4.66 |
Assets: | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Accrued receivables | Ìý | Ìý | Ìý | Ìý | 18,205 | Ìý | Ìý | Ìý | Ìý | $ 18,205 | Ìý |
Deferred tax asset | Ìý | Ìý | Ìý | Ìý | 6,992 | Ìý | Ìý | Ìý | Ìý | 6,992 | Ìý |
Liabilities and Capital: | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Unearned revenue | Ìý | Ìý | Ìý | Ìý | 41,375 | Ìý | Ìý | Ìý | Ìý | 41,375 | Ìý |
Other taxes payable | Ìý | Ìý | Ìý | Ìý | 433 | Ìý | Ìý | Ìý | Ìý | 433 | Ìý |
Net proceeds from all sources | Ìý | Ìý | Ìý | Ìý | 79,997 | Ìý | Ìý | Ìý | Ìý | 79,997 | Ìý |
Accounting Standards Update 2014-09 | New Revenue Standard Adjustment | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Consolidated Statements of Income: | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Revenue | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 22,305 | $ 6,198 |
Taxes, other than income taxes | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | (2,896) | (1,612) |
Income taxes - deferred | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 4,331 | 2,774 |
Net income | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 20,870 | $ 5,035 |
Net income per Sub-share Certificate (in dollars per share) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 2.66 | $ 0.63 |
Assets: | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Accrued receivables | Ìý | Ìý | Ìý | Ìý | (432) | Ìý | Ìý | Ìý | Ìý | $ (432) | Ìý |
Deferred tax asset | Ìý | Ìý | Ìý | Ìý | (7,106) | Ìý | Ìý | Ìý | Ìý | (7,106) | Ìý |
Liabilities and Capital: | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Unearned revenue | Ìý | Ìý | Ìý | Ìý | (33,011) | Ìý | Ìý | Ìý | Ìý | (33,011) | Ìý |
Other taxes payable | Ìý | Ìý | Ìý | Ìý | (433) | Ìý | Ìý | Ìý | Ìý | (433) | Ìý |
Net proceeds from all sources | Ìý | Ìý | Ìý | Ìý | $ 25,905 | Ìý | Ìý | Ìý | Ìý | $ 25,905 | Ìý |