Net Income Per Share - Calculation (Details) - USD ($) $ / shares in Units, $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2020 |
Sep. 30, 2020 |
Jun. 30, 2020 |
Mar. 31, 2020 |
Dec. 31, 2019 |
Sep. 30, 2019 |
Jun. 30, 2019 |
Mar. 31, 2019 |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
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| Net income - basic and diluted | $ 70,757 | $ 69,996 | $ 55,496 | $ 50,771 | $ 45,985 | $ 54,976 | $ 52,051 | $ 37,983 | $ 247,023 | $ 190,995 | $ 134,752 |
| Weighted average number of common shares outstanding - basic | 32,917,971 | 33,806,104 | 34,921,318 | ||||||||
| Dilutive effect of common stock equivalents: | |||||||||||
| Stock options | 138,354 | 225,049 | 281,932 | ||||||||
| Weighted average number of common shares outstanding - diluted | 33,299,986 | 34,376,555 | 35,613,319 | ||||||||
| Basic net income per common share | $ 2.16 | $ 2.13 | $ 1.69 | $ 1.53 | $ 1.38 | $ 1.63 | $ 1.53 | $ 1.11 | $ 7.50 | $ 5.65 | $ 3.86 |
| Diluted net income per common share | $ 2.13 | $ 2.11 | $ 1.67 | $ 1.51 | $ 1.36 | $ 1.60 | $ 1.51 | $ 1.09 | $ 7.42 | $ 5.56 | $ 3.78 |
| Service-based conditions | |||||||||||
| Dilutive effect of common stock equivalents: | |||||||||||
| Restricted stock awards | 51,324 | 87,159 | 151,324 | ||||||||
| Market-based conditions | |||||||||||
| Dilutive effect of common stock equivalents: | |||||||||||
| Restricted stock awards | 150,530 | 189,044 | 238,313 | ||||||||
| Performance-based conditions | |||||||||||
| Dilutive effect of common stock equivalents: | |||||||||||
| Restricted stock awards | 41,807 | 69,199 | 20,432 | ||||||||
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- Definition Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of restricted stock awards using the treasury stock method. No definition available.
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- Definition Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of stock options using the treasury stock method. No definition available.
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- Definition The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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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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- References No definition available.
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- Definition The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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