Debt - Summary of Outstanding Debt (Parenthetical) (Details)	6 Months Ended
Jun. 30, 2015
31 West 52nd Street [Member]
Debt Instrument [Line Items]
Ownership interest rate of property	64.20%
One Market Plaza [Member]
Debt Instrument [Line Items]
Ownership interest rate of property	49.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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Period Type:	duration