Goodwill and Other Intangible Assets (Details Textual) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2012	Dec. 31, 2011
Goodwill [Line Items]
Goodwill	$ 460,044,000	$ 460,044,000	$ 460,044,000	$ 460,044,000	$ 460,044,000	$ 460,044,000
Future Amortization Expense, Year One	900,000
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	$ 966,000	$ 1,086,000