Loans and Allowance for Loan Losses - Rollforward of Purchase Credit Impaired Loans (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($)
Gross Carrying Value
Gross carrying value, beginning balance	$ 12,468
Acquisitions	75,425
Year-to-date settlements	(2,919)
Gross carrying value, ending balance	84,974
Accretable Yield
Accretable yield, beginning balance	0
Acquisitions	(300)
Year-to-date settlements	2
Accretable yield, ending balance	(298)
Nonaccretable Yield
Nonaccretable yield, beginning balance	(3,633)
Acquisitions	(25,953)
Year-to-date settlements	796
Nonaccretable yield, ending balance	(28,790)
Net Carrying Value
Net carrying value, beginning balance	8,835
Acquisitions	49,172
Year-to-date settlements	(2,121)
Net carrying value, ending balance	$ 55,886