Income Taxes - Significant Components of The Company's Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Deferred tax assets
Allowance for credit losses	$ 39,448	$ 14,304
Loans	11,336	10,284
Deferred compensation	10,390	12,050
Impairment of assets	1,353	1,108
Net operating loss carryforwards	4,785	9,387
Lease liabilities under operating leases	22,357	22,686
Other	1,782	934
Total deferred tax assets	91,451	70,753
Deferred tax liabilities
Net unrealized gains on securities	5,507	190
Investment in partnerships	807	967
Fixed assets	2,951	2,952
Mortgage servicing rights	13,027	13,472
Junior subordinated debt	2,260	2,304
Lease right-of-use asset	21,354	21,727
Other	1,615	1,859
Total deferred tax liabilities	47,521	43,471
Net deferred tax assets	$ 43,930	$ 27,282