Goodwill And Intangible Assets (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Goodwill And Intangible Assets [Abstract]
Goodwill	$ 328,061,000		$ 328,061,000
Intangible assets, net	55,020,000		56,285,000
Amortization of intangible assets purchased	1,300,000	1,300,000
Accumulated amortization of intangible assets	$ 28,000,000		$ 26,700,000