Goodwill and Other Intangible Assets (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 741,740	$ 741,740	$ 741,740	$ 741,740	$ 741,740
Amortization of intangible assets	2,304	$ 2,598	4,608	$ 5,196
Remainder of 2016	4,600		4,600
2017	8,200		8,200
2018	7,300		7,300
2019	6,500		6,500
2020	$ 5,200		$ 5,200
Customer Relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Useful Life	12 years
Minimum | Core Deposits
Acquired Finite-Lived Intangible Assets [Line Items]
Useful Life	10 years
Maximum | Core Deposits
Acquired Finite-Lived Intangible Assets [Line Items]
Useful Life	15 years