Allowance for Loan Losses - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Receivables [Abstract]
Minimum period interest and principal of loans past due considered nonperforming (in days)	90 days
Evaluation for impairment of substandard and nonaccrual commercial loans	$ 500,000
Impaired financing receivables	41,935,000	$ 45,650,000
Acquired loans that experienced credit deterioration since acquisition	18,400,000
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Receivable, Net	5,615,212,000	5,062,933,000
Integrity Bancshares, Inc.
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses of acquired loans		0
Loans Receivable, Net	$ 543,300,000	$ 673,300,000