Loans and Allowance for Loan Losses - Changes in Accretable Yield and Nonaccretable Difference of Purchased Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Accounts Notes And Loans Receivable [Line Items]
Accretable yield, Beginning balance	$ (1,637)
Accretable yield, Accretion	3,538	$ 254
Accretable yield, Ending balance	(2,444)	(1,637)
Nonaccretable difference, Beginning balance	(8,369)
Nonaccretable difference, Ending balance	(4,459)	(8,369)
Beginning balance	(12,223)
Additions through acquisition		(12,514)
Principal reductions/ pay-offs		239
Adjustments to assumptions		(202)
Charge-offs	472
Sale of credit card portfolio	70
Accretion	3,538	254
Ending balance	(8,143)	(12,223)
Purchased Credit Impaired
Accounts Notes And Loans Receivable [Line Items]
Accretable yield, Beginning balance	(1,637)
Accretable yield, Additions through acquisition		(1,991)
Accretable yield, Principal reductions/ pay-offs	(3,438)	100
Accretable yield, Accretion	2,631	254
Accretable yield, Ending balance	(2,444)	(1,637)
Nonaccretable difference, Beginning balance	(8,369)
Nonaccretable difference, Additions through acquisition		(8,508)
Nonaccretable difference, Principal reductions/ pay-offs	3,438	139
Nonaccretable difference, Charge-offs	472
Nonaccretable difference, Ending balance	(4,459)	(8,369)
Purchased Non-impaired
Accounts Notes And Loans Receivable [Line Items]
Accretable yield, Beginning balance	(2,147)
Accretable yield, Additions through acquisition		(1,945)
Accretable yield, Adjustments to assumptions		(202)
Accretable yield, Accretion	907
Accretable yield, Ending balance	(1,240)	(2,147)
Nonaccretable difference, Beginning balance	(70)
Nonaccretable difference, Additions through acquisition		(70)
Nonaccretable difference, Sale of credit card portfolio	$ 70
Nonaccretable difference, Ending balance		$ (70)