Tax Credit Investments - Income Statement Disclosures (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Components of Income Tax Expense:
Affordable housing tax credits and other tax benefits	$ 1,393	$ 1,708	$ 2,627	$ 3,421
Other tax credit investment credits and tax benefits	2,540	2,158	3,840	4,961
Total reduction in income tax expense	3,933	3,866	6,467	8,382
Non-Interest Expenses
Amortization of Tax Credit Investments:
Affordable housing tax credit investment losses	537	593	1,091	1,266
Affordable housing tax credit investment impairment losses	665	794	1,083	1,524
Other tax credit investment losses	679	2,509	1,223	3,496
Other tax credit investment impairment losses	1,535	967	3,247	5,750
Total amortization of tax credit investments recorded in non-interest expense	$ 3,416	$ 4,863	$ 6,644	$ 12,036