Fair Value Measurements (Details) (Fair value measurement, recurring basis [Member], USD $)	Jun. 30, 2014		Dec. 31, 2013
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Fair value adjustment to the borrowings subject to TRS	$ 6,658,000		$ 8,869,000
Redeemable noncontrolling interest	(192,942,000)	[1]	(171,743,000)
Fair value of financial assets and liabilities and redeemable noncontrolling interests on a recurring basis	(296,176,000)		(284,923,000)
Interest rate caps [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative assets	214,000		155,000
Interest rate swap agreements [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative liabilities	(88,646,000)		(97,858,000)
Total Return Swap [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative assets	5,433,000		903,000
Derivative liabilities	(26,893,000)		(25,249,000)
Fair Value, Inputs, Level 1 [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Fair value adjustment to the borrowings subject to TRS	0		0
Redeemable noncontrolling interest	0		0
Fair value of financial assets and liabilities and redeemable noncontrolling interests on a recurring basis	0		0
Fair Value, Inputs, Level 1 [Member] | Interest rate caps [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative assets	0		0
Fair Value, Inputs, Level 1 [Member] | Interest rate swap agreements [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative liabilities	0		0
Fair Value, Inputs, Level 1 [Member] | Total Return Swap [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative assets	0		0
Derivative liabilities	0		0
Fair Value, Inputs, Level 2 [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Fair value adjustment to the borrowings subject to TRS	0		0
Redeemable noncontrolling interest	0		0
Fair value of financial assets and liabilities and redeemable noncontrolling interests on a recurring basis	(289,000)		(343,000)
Fair Value, Inputs, Level 2 [Member] | Interest rate caps [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative assets	214,000		155,000
Fair Value, Inputs, Level 2 [Member] | Interest rate swap agreements [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative liabilities	(503,000)		(498,000)
Fair Value, Inputs, Level 2 [Member] | Total Return Swap [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative assets	0		0
Derivative liabilities	0		0
Fair Value, Inputs, Level 3 [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Fair value adjustment to the borrowings subject to TRS	6,658,000		8,869,000
Redeemable noncontrolling interest	(192,942,000)	[1]	(171,743,000)
Fair value of financial assets and liabilities and redeemable noncontrolling interests on a recurring basis	(295,887,000)		(284,580,000)
Fair Value, Inputs, Level 3 [Member] | Interest rate caps [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative assets	0		0
Fair Value, Inputs, Level 3 [Member] | Interest rate swap agreements [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative liabilities	(88,143,000)		(97,360,000)
Fair Value, Inputs, Level 3 [Member] | Total Return Swap [Member]
Financial assets and liabilities and redeemable noncontrolling interests on a recurring basis
Derivative assets	5,433,000		903,000
Derivative liabilities	$ (26,893,000)		$ (25,249,000)

[1] As of June 30, 2014, the redeemable noncontrolling interest is recorded at book value.