Earnings per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Common Share [Line Items]
Conversion price (in dollars per share)	$ 101.38	$ 101.38	$ 101.38
Numerator — basic and diluted
Net income	$ 234,966	$ 210,682	$ 216,726
Denominator
Weighted average number of common shares outstanding — basic (in shares)	33,489	35,602	36,774
Effect of dilutive restricted shares (in shares)	701	763	820
Effect of dilutive stock options (in shares)	368	419	455
Effect of dilutive convertible notes (in shares)	779	365	62
Weighted average number of common shares outstanding — diluted (in shares)	35,337	37,149	38,111
Earnings per common share — basic (in dollars per share)	$ 7.02	$ 5.92	$ 5.89
Earnings per common share — diluted (in dollars per share)	$ 6.65	$ 5.67	$ 5.69
Stock Options And Restricted Shares
Denominator
Antidilutive stock options and restricted shares (in shares)	4	66	19