Loans and Allowance for Loan Losses - Changes in Accretable Yield and Nonaccretable Difference of Purchased Loans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Accounts Notes And Loans Receivable [Line Items]
Accretable yield, Beginning balance	$ (2,444)
Accretable yield, Accretion	1,160	$ 826
Accretable yield, Ending balance	(2,142)
Nonaccretable difference, Beginning balance	(4,459)
Nonaccretable difference, Ending balance	(3,756)
Beginning balance	(8,143)	(12,223)
Charge-offs	5	440
Recoveries	(23)
Sale of credit card portfolio		70
Accretion	1,160	826
Ending balance	(7,001)	(10,887)
Purchased Credit Impaired
Accounts Notes And Loans Receivable [Line Items]
Accretable yield, Beginning balance	(2,444)	(1,637)
Accretable yield, Principal reductions/ pay-offs	(698)	(231)
Accretable yield, Recoveries	(23)
Accretable yield, Accretion	1,023	408
Accretable yield, Ending balance	(2,142)	(1,460)
Nonaccretable difference, Beginning balance	(4,459)	(8,369)
Nonaccretable difference, Principal reductions/ pay-offs	698	231
Nonaccretable difference, Charge-offs	5	440
Nonaccretable difference, Ending balance	(3,756)	(7,698)
Purchased Non-impaired
Accounts Notes And Loans Receivable [Line Items]
Accretable yield, Beginning balance	(1,240)	(2,008)
Accretable yield, Accretion	137	418
Accretable yield, Ending balance	$ (1,103)	(1,590)
Nonaccretable difference, Beginning balance		(209)
Nonaccretable difference, Sale of credit card portfolio		70
Nonaccretable difference, Ending balance		$ (139)