Intangible Assets (Details 2) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Intangible Assets
Amortization expense during the year	$ 2,880,000	$ 2,960,000	$ 8,898,000	$ 8,814,000
Estimated aggregate amortization expense
Remainder of 2012	3,290,000		3,290,000
2013	11,510,000		11,510,000
2014	11,347,000		11,347,000
2015	11,312,000		11,312,000
2016	11,290,000		11,290,000
2017	$ 11,050,000		$ 11,050,000