Supplemental Cash Flow Information (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Supplemental cash flow information:
Interest paid, net of capitalized interest	$ 363,229	$ 339,190
Income taxes paid (refunded)	(2)	1,645
Capitalized interest	10,852	18,517
Supplemental schedule of non-cash investing activities:
Accrued construction costs	18,495	18,024
Fair value of real estate acquired in exchange for sale of real estate	15,204
Supplemental schedule of non-cash financing activities:
Vesting of restricted stock units	110	385
Cancellation of restricted stock	17	6
Conversion of non-managing member units into common stock	2,997	2,398
Noncontrolling interests issued in connection with acquisitions		27,432
Mortgages and other liabilities assumed with real estate acquisitions	12,728	35,120
Unrealized gains on available-for-sale securities and derivatives designated as cash flow hedges, net	$ 6,990	$ 2,203