Supplemental Cash Flow Information (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Supplemental cash flow information:
Interest paid, net of capitalized interest	$ 205,207	$ 192,853
Income taxes paid	1,995	1,682
Capitalized interest	8,036	13,495
Supplemental schedule of non-cash investing activities:
Accrued construction costs	17,585	18,522
Supplemental schedule of non-cash financing activities:
Vesting of restricted stock units	103	378
Cancellation of restricted stock	(16)	(4)
Conversion of non-managing member units into common stock	2,912	2,273
Mortgages and other liabilities assumed with real estate acquisitions	12,728
Unrealized gains (losses) on available-for-sale securities and derivatives designated as cash flow hedges, net	$ 10,700	$ (437)