Note 2 - Summary of Significant Accounting Policies - Adoption Impact of New Accounting Pronouncement Related to Revenue Recognition (Details) - USD ($) $ / shares in Units, $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2017 |
Sep. 30, 2017 |
Jun. 30, 2017 |
Mar. 31, 2017 |
Dec. 31, 2016 |
Sep. 30, 2016 |
Jun. 30, 2016 |
Mar. 31, 2016 |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
Revenue | $ 38,321 | $ 42,497 | $ 27,358 | $ 24,238 | $ 17,573 | $ 14,273 | $ 16,196 | $ 11,898 | $ 132,329 | $ 59,911 | $ 79,415 |
Taxes, other than income taxes | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 3,161 | 1,779 | 1,477 |
Income taxes — deferred | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | (3,365) | (4,194) | (186) |
Net income | $ 18,361 | $ 26,405 | $ 16,711 | $ 14,885 | $ 10,907 | $ 8,929 | $ 10,123 | $ 7,280 | $ 76,361 | $ 37,240 | $ 50,039 |
Net income per Sub-share Certificate (in dollars per share) | $ 2.35 | $ 3.36 | $ 2.12 | $ 1.88 | $ 1.37 | $ 1.12 | $ 1.26 | $ 0.90 | $ 9.72 | $ 4.66 | $ 6.10 |
ASSETS | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Accrued receivables | $ 18,205 | Ìý | Ìý | Ìý | $ 6,550 | Ìý | Ìý | Ìý | $ 18,205 | $ 6,550 | Ìý |
Deferred tax asset (liability) | 6,992 | Ìý | Ìý | Ìý | 3,875 | Ìý | Ìý | Ìý | 6,992 | 3,875 | Ìý |
LIABILITIES AND CAPITAL | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Unearned revenue | 41,375 | Ìý | Ìý | Ìý | 11,775 | Ìý | Ìý | Ìý | 41,375 | 11,775 | Ìý |
Other taxes payable | 433 | Ìý | Ìý | Ìý | 277 | Ìý | Ìý | Ìý | 433 | 277 | Ìý |
Net proceeds from all sources | 79,997 | Ìý | Ìý | Ìý | 48,584 | Ìý | Ìý | Ìý | 79,997 | 48,584 | Ìý |
Accounting Standards Update 2014-09 [Member] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Revenue | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 154,634 | 66,108 | Ìý |
Taxes, other than income taxes | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 265 | 167 | Ìý |
Income taxes — deferred | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 966 | (1,420) | Ìý |
Net income | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 97,231 | $ 42,275 | Ìý |
Net income per Sub-share Certificate (in dollars per share) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 12.38 | $ 5.29 | Ìý |
ASSETS | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Accrued receivables | 17,772 | Ìý | Ìý | Ìý | 6,273 | Ìý | Ìý | Ìý | $ 17,772 | $ 6,273 | Ìý |
Deferred tax asset (liability) | (114) | Ìý | Ìý | Ìý | 1,101 | Ìý | Ìý | Ìý | (114) | 1,101 | Ìý |
LIABILITIES AND CAPITAL | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Unearned revenue | 8,364 | Ìý | Ìý | Ìý | 3,966 | Ìý | Ìý | Ìý | 8,364 | 3,966 | Ìý |
Other taxes payable | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | ||||
Net proceeds from all sources | 105,902 | Ìý | Ìý | Ìý | 53,619 | Ìý | Ìý | Ìý | 105,902 | 53,619 | Ìý |
Scenario, Previously Reported [Member] | Accounting Standards Update 2014-09 [Member] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Revenue | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 132,329 | 59,911 | Ìý |
Taxes, other than income taxes | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 3,161 | 1,779 | Ìý |
Income taxes — deferred | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | (3,365) | (4,194) | Ìý |
Net income | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 76,361 | $ 37,240 | Ìý |
Net income per Sub-share Certificate (in dollars per share) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 9.72 | $ 4.66 | Ìý |
ASSETS | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Accrued receivables | 18,205 | Ìý | Ìý | Ìý | 6,550 | Ìý | Ìý | Ìý | $ 18,205 | $ 6,550 | Ìý |
Deferred tax asset (liability) | 6,992 | Ìý | Ìý | Ìý | 3,875 | Ìý | Ìý | Ìý | 6,992 | 3,875 | Ìý |
LIABILITIES AND CAPITAL | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Unearned revenue | 41,375 | Ìý | Ìý | Ìý | 11,775 | Ìý | Ìý | Ìý | 41,375 | 11,775 | Ìý |
Other taxes payable | 433 | Ìý | Ìý | Ìý | 277 | Ìý | Ìý | Ìý | 433 | 277 | Ìý |
Net proceeds from all sources | 79,997 | Ìý | Ìý | Ìý | 48,584 | Ìý | Ìý | Ìý | 79,997 | 48,584 | Ìý |
Restatement Adjustment [Member] | Accounting Standards Update 2014-09 [Member] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Revenue | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 22,305 | 6,197 | Ìý |
Taxes, other than income taxes | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | (2,896) | (1,612) | Ìý |
Income taxes — deferred | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 4,331 | 2,774 | Ìý |
Net income | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 20,870 | $ 5,035 | Ìý |
Net income per Sub-share Certificate (in dollars per share) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 2.66 | $ 0.63 | Ìý |
ASSETS | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Accrued receivables | (433) | Ìý | Ìý | Ìý | (277) | Ìý | Ìý | Ìý | $ (433) | $ (277) | Ìý |
Deferred tax asset (liability) | (7,106) | Ìý | Ìý | Ìý | (2,774) | Ìý | Ìý | Ìý | (7,106) | (2,774) | Ìý |
LIABILITIES AND CAPITAL | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Unearned revenue | (33,011) | Ìý | Ìý | Ìý | (7,809) | Ìý | Ìý | Ìý | (33,011) | (7,809) | Ìý |
Other taxes payable | (433) | Ìý | Ìý | Ìý | (277) | Ìý | Ìý | Ìý | (433) | (277) | Ìý |
Net proceeds from all sources | $ 25,905 | Ìý | Ìý | Ìý | $ 5,035 | Ìý | Ìý | Ìý | $ 25,905 | $ 5,035 | Ìý |