Income Taxes (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2011 Agreement	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Income Taxes [Abstract]
Percentage of actual tax liability to capital gain	100.00%
Income taxes paid, net	$ 41,200,000	$ 25,900,000	$ 234,600,000
Tax liabilities	34,800,000	37,900,000
Number of agreements terminated without liability	2
Change in uncertain tax positions	9,000,000	11,800,000	3,700,000
Income taxes paid for tax settlements	24,500,000
Income Taxes (Textual) [Abstract]
Recognized expense/benefit	21,579,000	21,724,000	29,262,000
Recognized expense		11,800,000
Recognized benefit		3,700,000
Cash paid for income taxes, net of refunds	41,200,000	25,900,000	234,600,000
Unrecognized tax liability, interest and penalties				85,400,000
Payment for closing agreement and settlement of state tax audits	24,500,000
Accrued interest and penalties	26,400,000	43,700,000
Accrued interest and penalties	$ 26,400,000	$ 43,700,000