Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income taxes currently payable	$ 21,500	$ 19,329	$ 46,566	$ 51,000
Deferred income taxes	(2,730)	(1,696)	3,585	2,920
Actual tax provision	$ 18,770	$ 17,633	$ 50,151	$ 53,920