Tax Credit Investments - Income Statement Disclosures (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Components of Income Tax Expense:
Affordable housing tax credits and other tax benefits	$ 1,234	$ 1,713
Other tax credit investment credits and tax benefits	1,300	2,803
Total reduction in income tax expense	2,534	4,516
Non-Interest Expenses
Amortization of Tax Credit Investments:
Affordable housing tax credit investment losses	554	673
Affordable housing tax credit investment impairment losses	418	730
Other tax credit investment losses	544	987
Other tax credit investment impairment losses	1,712	4,783
Total amortization of tax credit investments recorded in non-interest expense	$ 3,228	$ 7,173