Basis of Presentation and Significant Accounting Policies (Details 2) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Tax Treatment Of Dividend [Line Items]
Minimum Percentage of Taxable Income Distributed As Dividends				90.00%
Percentage Of Taxable Income Distributed				100.00%
Income Tax Expense Benefit Continuing Operations Income Tax Reconciliation [Line Items]
Deferred Tax Assets, Valuation Allowance	$ 95,419,000			$ 95,419,000		$ 94,100,000
Proceeds from sale of real estate		$ 10,731,000
Deferred tax assets allowance, reversed	90,030,000			90,030,000	$ 0
Income tax benefit	$ (88,072,000)		$ 3,280,000	(87,101,000)	$ 4,131,000
New York Manhattan 220 Central Park South Site [Member]
Income Tax Expense Benefit Continuing Operations Income Tax Reconciliation [Line Items]
Percentage of number of units sold			40.00%		40.00%
Proceeds from sale of real estate				$ 1,400,000,000