Derivative Instruments and Hedging Activities (Details 1) - Cash Flow Hedging [Member] - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivative instruments gain (loss) in financial statements
Gain (loss) recognized in OCI (effective portion)	$ (7,854,000)	$ 1,288,000	$ (15,557,000)	$ (10,166,000)
Gain (loss) reclassified from accumulated OCI, effective amount	(10,644,000)	(10,563,000)	(30,011,000)	(31,417,000)
Gain (loss) reclassified from accumulated OCI, ineffective amount	(16,000)	(1,000)	(28,000)	(3,667,000)
Interest rate caps and interest rate swaps [Member]
Derivative instruments gain (loss) in financial statements
Gain (loss) recognized in OCI (effective portion)	(7,854,000)	1,288,000	(15,557,000)	(10,166,000)
Interest rate caps and interest rate swaps [Member] | Interest expense [Member]
Derivative instruments gain (loss) in financial statements
Gain (loss) reclassified from accumulated OCI, effective amount	(9,759,000)	(9,561,000)	(28,060,000)	(28,412,000)
Gain (loss) reclassified from accumulated OCI, ineffective amount	(16,000)	(1,000)	(27,000)	(1,000)
Interest rate caps and interest rate swaps [Member] | Net Gain on Change in Control of Interests [Member]
Derivative instruments gain (loss) in financial statements
Gain (loss) reclassified from accumulated OCI, effective amount	0		900,000
Gain (loss) reclassified from accumulated OCI, ineffective amount	0		0
Interest rate caps and interest rate swaps [Member] | Earnings (loss) from Unconsolidated Entities, Gross of Tax [Member]
Derivative instruments gain (loss) in financial statements
Gain (loss) reclassified from accumulated OCI, effective amount	(885,000)	(1,002,000)	(2,851,000)	(3,005,000)
Gain (loss) reclassified from accumulated OCI, ineffective amount	$ 0	$ 0	$ (1,000)	0
Interest rate caps and interest rate swaps [Member] | Discontinued operations [Member]
Derivative instruments gain (loss) in financial statements
Gain (loss) reclassified from accumulated OCI, effective amount				0
Gain (loss) reclassified from accumulated OCI, ineffective amount				$ (3,666,000)