Tax Credit Investments - Affordable Housing Tax Credit Investments and Other Tax Credit Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Components of Income Tax Expense:
Affordable housing tax credits and other tax benefits	$ 5,414	$ 6,757	$ 6,713
Other tax credit investment credits and tax benefits	8,065	10,205	21,351
Total reduction in income tax expense	13,479	16,962	28,064
Amortization Recorded in Non-Interest Expenses
Amortization of Tax Credit Investments:
Affordable housing tax credit investment losses	2,714	2,184	1,880
Affordable housing tax credit investment impairment losses	2,209	3,295	2,544
Other tax credit investment losses	2,234	5,668	1,970
Other tax credit investment impairment losses	6,178	9,245	17,806
Total amortization of tax credit investments recorded in non-interest expense	$ 13,335	$ 20,392	$ 24,200