Supplemental Cash Flow Information (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Supplemental cash flow information:
Interest paid, net of capitalized interest	$ 204,590	$ 205,207
Income taxes paid	3,380	1,995
Capitalized interest	5,983	8,036
Supplemental schedule of non-cash investing activities:
Accrued construction costs	25,069	17,585
Noncontrolling interest disposed in connection with real estate sales	1,671
Supplemental schedule of non-cash financing activities:
Vesting of restricted stock units	567	103
Cancellation of restricted stock	(1)	(16)
Conversion of non-managing member units into common stock	73	2,912
Noncontrolling interest issued in connection with real estate acquisition	6,321
Mortgages and other liabilities assumed with real estate acquisitions	523	12,728
Unrealized gains (losses) on available-for-sale securities and derivatives designated as cash flow hedges, net	$ (696)	$ 10,700