Income Taxes - Deferred taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Allowance for loan losses	$ 14,910	$ 14,604
Net operating loss carryforwards	27,568	39,204
Deferred compensation	9,363	8,535
Loan purchase accounting adjustments	6,599	8,658
Reserve for losses on foreclosed properties	20	61
Nonqualified share based compensation	2,041	1,190
Accrued expenses	3,958	3,536
Investment in partnerships	67	426
Unamortized pension actuarial losses and prior service cost	1,739	1,606
Unrealized losses on securities available-for-sale	0	8,092
Unrealized losses on cash flow hedges	0	86
Lease liability	5,327	0
Other	2,038	1,235
Total deferred tax assets	73,630	87,233
Deferred tax liabilities:
Unrealized gains on securities available-for-sale	7,943	0
Acquired intangible assets	2,530	2,772
Premises and equipment	3,002	1,291
Loan origination costs	3,538	3,734
True tax leases	7,783	6,020
Prepaid expenses	373	398
Servicing assets	4,428	2,862
Derivatives	1,075	525
Right-of-use asset	4,809	0
Uncertain tax positions	1,792	2,036
Total deferred tax liabilities	37,273	19,638
Less valuation allowance	2,298	3,371
Net deferred tax asset	$ 34,059	$ 64,224