Investment in Unconsolidated Joint Venture (Details) (USD $)	3 Months Ended				3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Oct. 15, 2013	Mar. 31, 2014 Worldwide Plaza	Dec. 31, 2013 Worldwide Plaza	Oct. 30, 2013 Worldwide Plaza
Schedule of Equity Method Investments [Line Items]
Ownership percentage				48.90%			48.90%
Aggregate cost							$ 220,100,000
Agreed upon value							1,325,000,000
Notes payable					875,000,000	875,000,000	875,000,000
Interest rate							4.60%
Investments in unconsolidated joint ventures	229,127,000		234,774,000
Purchase option term					38 months
Purchase obligation					1,400,000,000
Difference between carrying amount and underlying equity							260,600,000
Difference between carrying amount and equity	3,200,000
Income from unconsolidated joint venture	1,257,000	0			1,257,000
Proceeds from investment					$ 3,851,000