Loans and Allowance for Loan Losses - Changes in Accretable Yield and Nonaccretable Difference of Purchased Loans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accounts Notes And Loans Receivable [Line Items]
Accretable yield, Beginning balance			$ (2,444)
Accretable yield, Accretion			848	$ 2,381
Accretable yield, Ending balance	$ (1,845)		(1,845)
Nonaccretable difference, Beginning balance			(4,459)
Nonaccretable difference, Ending balance	(3,464)		(3,464)
Beginning balance	(7,001)	$ (10,887)	(8,143)	(12,223)
Charge-offs		32	5	472
Recoveries			(23)
Sale of credit card portfolio				70
Accretion	848	1,555	2,008	2,381
Ending balance	(6,153)	(9,300)	(6,153)	(9,300)
Purchased Credit Impaired
Accounts Notes And Loans Receivable [Line Items]
Accretable yield, Beginning balance	(2,142)	(1,460)	(2,444)	(1,637)
Accretable yield, Principal reductions/ pay-offs	(292)	(1,227)	(990)	(1,458)
Accretable yield, Recoveries			(23)
Accretable yield, Accretion	589	1,439	1,612	1,847
Accretable yield, Ending balance	(1,845)	(1,248)	(1,845)	(1,248)
Nonaccretable difference, Beginning balance	(3,756)	(7,698)	(4,459)	(8,369)
Nonaccretable difference, Principal reductions/ pay-offs	292	1,227	990	1,458
Nonaccretable difference, Charge-offs		32	5	472
Nonaccretable difference, Ending balance	(3,464)	(6,439)	(3,464)	(6,439)
Purchased Non-impaired
Accounts Notes And Loans Receivable [Line Items]
Accretable yield, Beginning balance	(1,103)	(1,729)	(1,240)	(2,147)
Accretable yield, Accretion	259	116	396	534
Accretable yield, Ending balance	$ (844)	$ (1,613)	$ (844)	(1,613)
Nonaccretable difference, Beginning balance				(70)
Nonaccretable difference, Sale of credit card portfolio				$ 70