Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Income taxes currently payable	$ 13,930	$ 9,391	$ 25,066	$ 31,671
Deferred income taxes	3,088	6,202	6,315	4,616
Actual tax provision	$ 17,018	$ 15,593	$ 31,381	$ 36,287