Assets and Liabilities Measured at Fair Value - Reconciliation for measurements at fair value on a recurring basis using significant unobservable inputs (Details) - Recurring - Level 3 - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Asset
Reconciliation of Assets at Level 3 Measurement
Balance at beginning of period	$ 12,207	$ 11,777	$ 9,418
Transfer from amortization method to fair value		0
Business combinations	0	0
Additions	0	0	0
Sales and settlements	(1,029)	(1,744)	(509)
Other comprehensive income	0	0	0
Amounts included in earnings - fair value adjustments	663	2,174	2,868
Balance at end of period	11,841	12,207	11,777
Servicing rights for SBA/USDA loans
Reconciliation of Assets at Level 3 Measurement
Balance at beginning of period	7,740	5,752	3,712
Transfer from amortization method to fair value		0
Business combinations	(354)	419
Additions	2,573	2,737	2,723
Sales and settlements	(810)	(621)	(393)
Other comprehensive income	0	0	0
Amounts included in earnings - fair value adjustments	(1,639)	(547)	(290)
Balance at end of period	7,510	7,740	5,752
Residential mortgage servicing rights
Reconciliation of Assets at Level 3 Measurement
Balance at beginning of period	8,262	0	0
Transfer from amortization method to fair value		5,070
Business combinations	0	0
Additions	4,587	3,602	0
Sales and settlements	(537)	(328)	0
Other comprehensive income	0	0	0
Amounts included in earnings - fair value adjustments	(435)	(82)	0
Balance at end of period	11,877	8,262	0
Debt Securities Available- for-Sale
Reconciliation of Assets at Level 3 Measurement
Balance at beginning of period	900	675	750
Transfer from amortization method to fair value		0
Business combinations	0	0
Additions	0	0	0
Sales and settlements	0	0	0
Other comprehensive income	95	225	(75)
Amounts included in earnings - fair value adjustments	0	0	0
Balance at end of period	995	900	675
Derivative Liability
Reconciliation of Liabilities at Level 3 Measurement
Balance at beginning of period	16,744	16,347	15,794
Transfer from amortization method to fair value		0
Business combinations	0	0
Additions	0	0	17
Sales and settlements	(1,347)	(2,423)	(1,001)
Other comprehensive income	0	0	0
Amounts included in earnings - fair value adjustments	335	2,820	1,537
Balance at end of period	$ 15,732	$ 16,744	$ 16,347