Net Income Per Common Share - Computation of Basic and Diluted Net Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Earnings Per Share [Abstract]
Net income	$ 91,038	$ 143,068	$ 307,454	$ 386,121
Computation of basic and diluted net income per common share
Weighted average common shares outstanding during the period (for basic calculation) (in shares)	38,848	39,675	39,286	39,648
Dilutive effect of other potential common shares (in shares)	215	308	235	201
Weighted average common shares and potential common shares (for diluted calculation) (in shares)	39,063	39,983	39,521	39,849
Net income per common share - Basic (in dollars per share)	$ 2.34	$ 3.61	$ 7.83	$ 9.74
Net income per common share - Diluted (in dollars per share)	$ 2.33	$ 3.58	$ 7.78	$ 9.69