Loans and Allowance for Loan Losses - Net (Charge-Offs)/Recoveries, Excluding Loans Acquired, Segregated by Class of Loans (Details) - Loans, Excluding Acquired Loans - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	$ (19,918)	$ (19,145)	$ (14,504)
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	(9,126)	(4,412)
Consumer | Credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	(3,046)	(2,884)	(2,288)
Consumer | Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	(6,080)	(1,528)
Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	(4,914)	(6,999)	(7,166)
Real Estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	(1,775)	100
Real Estate | Single family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	(494)	(1,045)
Real Estate | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	(2,645)	(6,054)
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	(5,878)	(7,734)	$ (3,591)
Commercial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	(5,878)	(7,734)
Commercial | Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net (charge-offs)/recoveries	$ 0	$ 0