Cash Flow Disclosures, Supplemental (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Interest Paid, Capitalized	$ 8,672,000	$ 5,392,000
Interest Paid, Net	12,800,000	18,200,000
Income Taxes Paid, Net	200,000	5,500,000
Partnership Units Received as Part of Consideration in Connection with Sale of Equity Method Investment and Other Assets, Fair Value at Acquisition Date		77,711,000
Issuance of partnership units in connection with the purchase of the U.S. headquarters building		91,000
Noncash or Part Noncash Acquisition, Debt Assumed including Unamortized Premium		18,215,000
Capital Expenditures Incurred but Not yet Paid	$ 44,559,000	$ 43,664,000