Indebtedness - Overview (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Indebtedness [Abstract]
Debt, Weighted Average Interest Rate	5.80%	6.20%	6.20%
Interest Costs, Capitalized During Period	$ 3,000,000	$ 929,000	$ 7,600,000
Interest Paid	$ 134,300,000	$ 145,800,000	$ 159,700,000