Tax Credit Investments - Income Statement Disclosures (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Components of Income Tax Expense:
Affordable housing tax credits and other tax benefits	$ 1,352	$ 1,666	$ 3,979	$ 5,087
Other tax credit investment credits and tax benefits	1,727	1,902	5,567	6,863
Total reduction in income tax expense	3,079	3,568	9,546	11,950
Non-Interest Expenses
Amortization of Tax Credit Investments:
Affordable housing tax credit investment losses	642	530	1,733	1,796
Affordable housing tax credit investment impairment losses	585	857	1,668	2,381
Other tax credit investment losses	12	1,093	1,235	4,589
Other tax credit investment impairment losses	1,520	1,905	4,767	7,655
Total amortization of tax credit investments recorded in non-interest expense	$ 2,759	$ 4,385	$ 9,403	$ 16,421