Loans and Allowance for Loan Losses - Rollforward of Purchase Credit Impaired Loans (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Gross Carrying Value
Gross carrying value, beginning balance	$ 42,837
Acquisitions	0
Year-to-date settlements	(2,951)
Gross carrying value, ending balance	39,886
Accretable Yield
Accretable yield, beginning balance	(114)
Acquired Accretable Yield	0
Year-to-date settlements	12
Accretable yield, ending balance	(102)
Nonaccretable Yield
Nonaccretable yield, beginning balance	(17,394)
Acquired Nonaccretable Yield	0
Year-to-date settlements	1,312
Nonaccretable yield, ending balance	(16,082)
Net Carrying Value
Net carrying value, beginning balance	25,329
Acquisitions	0
Year-to-date settlements	(1,627)
Net carrying value, ending balance	$ 23,702