Income Taxes (Details) (USD $)	3 Months Ended			9 Months Ended
	Sep. 30, 2011	Jun. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Income Taxes [Abstract]
Recognized income tax provision	$ 18,478,000		$ 6,695,000	$ 48,939,000	$ 14,266,000
Unrecognized tax benefits resulting in the reversal of accrued liability		1,100,000
Effective tax rate excluding discrete items	37.40%		42.60%	37.50%	42.60%
Charge due to the matter discussed	5,900,000			5,900,000
Income tax receivables	8,300,000			8,300,000		41,200,000
Liability for unrecognized tax benefits	18,700,000			18,700,000		15,900,000
Accrued interest and penalties	$ 6,900,000			$ 6,900,000		$ 6,100,000