Income Taxes - Significant Components of The Company's Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Deferred tax assets
Allowance for credit losses	$ 52,345	$ 53,597
Loans	3,471	5,526
Deferred compensation	13,598	13,114
Investment in partnerships	154	0
Impairment of assets	508	1,067
Net operating loss carryforwards	1,287	1,857
Lease liabilities under operating leases	17,189	17,732
Other	3,613	3,539
Total deferred tax assets	92,165	96,432
Deferred tax liabilities
Net unrealized gains on securities	3,580	8,434
Investment in partnerships	0	793
Fixed assets	1,182	3,285
Mortgage servicing rights	20,587	14,623
Junior subordinated debt	2,162	2,245
Intangibles	3,349	3,882
Lease right-of-use asset	16,291	16,833
Other	565	1,672
Total deferred tax liabilities	47,716	51,767
Net deferred tax assets	$ 44,449	$ 44,665