Loans - Acquired Loans (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Credit impaired acquired loans:
Outstanding principal balance	$ 23,182		$ 30,694
Recorded investment	20,416		25,188
Discount, net	2,766		5,506
Other acquired loans:
Outstanding principal balance	568,529		775,709
Recorded investment	566,106		771,104
Discount, net	2,346		4,431
Total acquired loans:
Outstanding principal balance	591,711		806,403
Deferred fees, net	(77)		(174)
Recorded investment	586,522		796,292
Discount, net	5,112		$ 9,937
Changes in the accretable yield for credit impaired acquired loans
Beginning balance	2,544	$ 967
Reclassifications from nonaccretable yield	(422)	3,087
Accretion	(1,166)	(1,051)
Balance at period end	$ 956	$ 3,003