Goodwill and Other Intangible Assets (Details Textual) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Goodwill [Line Items]
Goodwill	$ 460,044,000	$ 460,044,000	$ 460,044,000	$ 460,044,000
Future Amortization Expense, Year One	1,400,000
Future Amortization Expense, Year Two	1,200,000
Future Amortization Expense, Year Three	1,100,000
Future Amortization Expense, Year Four	1,000,000
Future Amortization Expense, Year Five	900,000
Amortization of Intangible Assets	$ 483,000	$ 543,000