Summary of Significant Accounting Policies (Details 7) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash expenditures for interest and income taxes [Abstract]
Interest, net of amount capitalized	$ 78,133,000	$ 80,962,000	$ 81,267,000
Income taxes paid (refunded), net	(12,287,000)	46,892,000	39,807,000
Capital Expenditures Not Included in Cash Flows from Investing Activities	$ 24,000,000