Mergers and Acquisitions (Details Textual) $ in Thousands	Jul. 01, 2017 USD ($) branch shares	Apr. 01, 2016 USD ($) branch shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Business Acquisition [Line Items]
Goodwill			$ 611,046	$ 470,534	$ 445,871
Metropolitan Bancgroup, Inc.
Business Acquisition [Line Items]
Transaction value	$ 219,461
Shares issued to common shareholders (shares) | shares	4,883,182
Cash settlement for stock options	$ 4,764
Percentage of voting interests acquired (percent)	100.00%
Number of locations acquired | branch	8
Intangible assets	$ 147,478
Goodwill	140,512
Intangible acquired	$ 6,966
Useful life (in years)	10 years
Total net assets acquired	$ 78,949
Borrowings	$ 174,522
KeyWorth Bank
Business Acquisition [Line Items]
Transaction value		$ 58,884
Percentage of voting interests acquired (percent)		100.00%
Intangible assets		$ 22,643
Goodwill		20,633
Intangible acquired		$ 2,010
Useful life (in years)		10 years
Consideration paid to stock option and warrant holders		$ 3,594
Total net assets acquired		415,232
Borrowings		$ 272,330
Number of offices in operation | branch		6
KeyWorth Bank | Core deposit intangible
Business Acquisition [Line Items]
Deposits assumed		$ 348,961
KeyWorth Bank | Common Stock
Business Acquisition [Line Items]
Shares issued to common shareholders (shares) | shares		1,680,021