Financial Instruments: Derivatives and Hedging (Details) (USD $)	3 Months Ended			9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013	Dec. 31, 2013
Financial Instruments: Derivatives and Hedging
Derivative, Net Liability Position, Aggregate Fair Value	$ 14,700,000			$ 14,700,000
Fair Value, liabilities	(14,114,000)			(14,114,000)			(1,329,000)
Fair Value, net	(14,035,000)			(14,035,000)
Aggregate termination value of derivative	14,700,000			14,700,000
Estimated current balance held in accumulated other comprehensive loss to be reclassified into earnings within the next 12 months				6,700,000
Share of joint venture of accumulated other comprehensive loss reclassified into equity in net income from unconsolidated joint ventures within the next 12 months				1,000,000
Amount of Gain or (Loss) Recognized in Other Comprehensive Loss (Effective Portion)	2,052,000		(2,766,000)	5,720,000		5,483,000
Amount of Loss Reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion)	1,867,000		1,601,000	5,660,000		5,039,000
Amount of Gain or (Loss) or Recognized into Income (Ineffective Portion)	1,000		7,000	3,000		2,000
Interest Rate Cap expiring in May 2016
Financial Instruments: Derivatives and Hedging
Notional Value (in thousands)	946,000,000			946,000,000
Strike Rate (as a percent)	4.75%			4.75%
Fair Value, assets	52,000			52,000
Interest Rate Cap expiring In May 2016
Financial Instruments: Derivatives and Hedging
Notional Value (in thousands)	504,000,000			504,000,000
Strike Rate (as a percent)	4.75%			4.75%
Fair Value, assets	27,000			27,000
Interest Rate Cap- Sold expiring in May 2016
Financial Instruments: Derivatives and Hedging
Notional Value (in thousands)	504,000,000			504,000,000
Strike Rate (as a percent)	4.75%			4.75%
Fair Value, liabilities	(27,000)			(27,000)
Interest Rate Cap expiring in November, 2015
Financial Instruments: Derivatives and Hedging
Notional Value (in thousands)	263,426,000			263,426,000
Strike Rate (as a percent)	6.00%			6.00%
Fair Value, assets	0			0
Interest Rate Cap expiring in September 2015
Financial Instruments: Derivatives and Hedging
Notional Value (in thousands)	137,500,000			137,500,000
Strike Rate (as a percent)	4.00%			4.00%
Fair Value, assets	0			0
Interest Rate Swap expiring in December 2017
Financial Instruments: Derivatives and Hedging
Notional Value (in thousands)	144,000,000	[1]		144,000,000	[1]
Strike Rate (as a percent)	2.236%	[1]		2.236%	[1]
Fair Value, liabilities	(4,603,000)	[1]		(4,603,000)	[1]
Interest Rate Swap expiring in December 2017
Financial Instruments: Derivatives and Hedging
Notional Value (in thousands)	72,000,000	[1]		72,000,000	[1]
Strike Rate (as a percent)	2.31%	[1]		2.31%	[1]
Fair Value, liabilities	(2,470,000)	[1]		(2,470,000)	[1]
Interest Rate Swap expiring in December 2017
Financial Instruments: Derivatives and Hedging
Notional Value (in thousands)	72,000,000	[1]		72,000,000	[1]
Strike Rate (as a percent)	2.31%	[1]		2.31%	[1]
Fair Value, liabilities	(2,467,000)	[1]		(2,467,000)	[1]
Interest Rate Swap expiring in December 2017
Financial Instruments: Derivatives and Hedging
Notional Value (in thousands)	57,600,000	[1]		57,600,000	[1]
Strike Rate (as a percent)	1.99%	[1]		1.99%	[1]
Fair Value, liabilities	(1,392,000)	[1]		(1,392,000)	[1]
Interest Rate Swap expiring in December 2017
Financial Instruments: Derivatives and Hedging
Notional Value (in thousands)	86,400,000	[1]		86,400,000	[1]
Strike Rate (as a percent)	1.948%	[1]		1.948%	[1]
Fair Value, liabilities	(1,972,000)	[1]		(1,972,000)	[1]
Interest Rate Swap expiring in December 2017
Financial Instruments: Derivatives and Hedging
Notional Value (in thousands)	72,000,000	[1]		72,000,000	[1]
Strike Rate (as a percent)	1.345%	[1]		1.345%	[1]
Fair Value, liabilities	(273,000)	[1]		(273,000)	[1]
Interest Rate Cap expiring in June, 2016
Financial Instruments: Derivatives and Hedging
Notional Value (in thousands)	30,000,000			30,000,000
Strike Rate (as a percent)	2.295%			2.295%
Fair Value, liabilities	(893,000)			(893,000)
Interest Rate Swap expiring in February, 2015
Financial Instruments: Derivatives and Hedging
Notional Value (in thousands)	8,500,000			8,500,000
Strike Rate (as a percent)	0.74%			0.74%
Fair Value, liabilities	(17,000)			(17,000)
Interest Rate Swap
Financial Instruments: Derivatives and Hedging
Amount of Gain or (Loss) Recognized in Other Comprehensive Loss (Effective Portion)	1,761,000		(160,000)	1,245,000		(20,000)
Amount of Loss Reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion)	1,826,000		320,000	3,790,000		1,258,000
Amount of Gain or (Loss) or Recognized into Income (Ineffective Portion)	1,000		2,000	3,000		2,000
Share of unconsolidated joint ventures' derivative instruments
Financial Instruments: Derivatives and Hedging
Amount of Gain or (Loss) Recognized in Other Comprehensive Loss (Effective Portion)	291,000		(2,606,000)	4,475,000		5,503,000
Amount of Loss Reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion)	41,000		1,281,000	1,870,000		3,781,000
Amount of Gain or (Loss) or Recognized into Income (Ineffective Portion)	$ 0		$ 5,000	$ 0		$ 0

[1] As a result of the acquisition and consolidation of 388-390 Greenwich Street, we have assumed these derivative instruments and have designated them as hedges.