Long-Term Borrowings and Subordinated Debt - Additional Information (Details) - USD ($)	Jun. 18, 2015	Mar. 05, 2015	Dec. 31, 2016	Dec. 31, 2015	Mar. 04, 2015
Debt Instrument [Line Items]
Long-term borrowings			$ 14,700,000	$ 117,000,000
Total loans pledged as collateral			3,200,000,000
Maximum eligible borrowing based on qualifying collateral			1,400,000,000.0
Maximum borrowing capacity			2,300,000,000.0
Capital lease			$ 100,000
Percentage of equity owned			100.00%
2006 Junior Subordinated Debt | Integrity Bancshares, Inc.
Debt Instrument [Line Items]
Junior subordinated debt assumed on acquisition					$ 13,500,000
Junior subordinated debt paid off	$ 5,000,000	$ 8,500,000