Indebtedness - Overview (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Debt Disclosure [Abstract]
Debt, Weighted Average Interest Rate	5.30%	5.80%	6.20%
Interest Costs, Capitalized During Period	$ 9,900,000	$ 3,011,000	$ 929,000
Interest Paid	$ 132,200,000	$ 134,300,000	$ 145,800,000