Mergers and Acquisitions - (Details Textual) $ in Thousands	Jan. 17, 2017 shares	Apr. 01, 2016 USD ($) branch shares	Mar. 31, 2017 USD ($) branch	Dec. 31, 2016 USD ($)	Mar. 31, 2016 USD ($)
Business Acquisition [Line Items]
Goodwill resulting from merger			$ 470,534	$ 470,534	$ 449,425
Metropolitan Bancgroup, Inc.
Business Acquisition [Line Items]
Shares to be issued per each common stock share of Metropolitan common stock (in shares) | shares	0.6066
Number of offices in operation | branch			8
Assets acquired			$ 1,164,500
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Financial Assets			929,700
Deposits			$ 945,100
KeyWorth Bank
Business Acquisition [Line Items]
Number of offices in operation | branch		6
Assets acquired		$ 415,232
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Financial Assets		272,330
Transaction value		58,884
Payment to stock option holders		$ 3,594
Voting interest acquired (percent)		100.00%
Intangible assets, including goodwill		$ 22,643
Goodwill resulting from merger		20,633
Core deposit intangible		$ 2,010
Weighted average useful life (in years)		10 years
KeyWorth Bank | Core Deposits
Business Acquisition [Line Items]
Deposits		$ 348,961
KeyWorth Bank | Common Stock
Business Acquisition [Line Items]
Shares issued to common shareholders (shares) | shares		1,680,021