Income Taxes - Significant Components of The Company's Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Deferred tax assets
Allowance for credit losses	$ 53,318	$ 53,597
Loans	4,883	5,526
Deferred compensation	12,311	13,114
Impairment of assets	874	1,067
Net operating loss carryforwards	1,667	1,857
Lease liabilities under operating leases	18,168	17,732
Other	3,504	3,539
Total deferred tax assets	94,725	96,432
Deferred tax liabilities
Net unrealized gains on securities	6,804	8,434
Investment in partnerships	719	793
Fixed assets	2,534	3,285
Mortgage servicing rights	19,025	14,623
Junior subordinated debt	2,223	2,245
Intangibles	3,968	3,882
Lease right-of-use asset	17,239	16,833
Other	1,459	1,672
Total deferred tax liabilities	53,971	51,767
Net deferred tax assets	$ 40,754	$ 44,665