Goodwill and Other Intangible Assets (Details Textual) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 460,044,000	$ 460,044,000	$ 460,044,000
Amortization of Intangible Assets	317,000	483,000
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	900,000
Finite-Lived Intangible Assets, Amortization Expense, Year Two	1,100,000
Finite-Lived Intangible Assets, Amortization Expense, Year Three	1,000,000
Finite-Lived Intangible Assets, Amortization Expense, Year Four	900,000
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 800,000
Core Deposits [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Useful Life	10 years