Income Taxes - Components of Federal Corporate Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Current income tax expense	$ 37,314	$ 30,634	$ 28,316
Deferred income tax expense	(1,961)	(1,849)	789
Income tax expense	$ 35,353	$ 28,785	$ 29,105