Income Taxes - Deferred taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Allowance for loan losses	$ 14,604	$ 14,092
Net operating loss carryforwards	39,204	56,428
Deferred compensation	8,535	7,760
Loan purchase accounting adjustments	8,658	14,478
Reserve for losses on foreclosed properties	61	402
Nonqualified share based compensation	1,190	1,182
Accrued expenses	3,536	4,290
Investment in partnerships	426	956
Unamortized pension actuarial losses and prior service cost	1,606	2,008
Unrealized losses on securities available-for-sale	8,092	2,430
Unrealized losses on cash flow hedges	86	108
Premises and equipment	0	1,040
Other	1,235	3,065
Total deferred tax assets	87,233	108,239
Deferred tax liabilities:
Acquired intangible assets	2,772	3,734
Premises and equipment	1,291	0
Loan origination costs	3,734	3,881
Leases	6,020	0
Prepaid expenses	398	468
Servicing assets	2,862	3,757
Derivatives	525	773
Uncertain tax positions	2,036	3,163
Total deferred tax liabilities	19,638	15,776
Less valuation allowance	3,371	4,414
Net deferred tax asset	$ 64,224	$ 88,049