Corporate Indebtedness (Details 3) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014
Amortization and Maturities of Long-term Debt [Abstract]
Remaining 2014	$ 157,288
2015	374,245
2016	648,228
2017	1,502,650
2018	558,462
Thereafter	5,534,634
Total amortization of debt and principal repayments	8,775,507
Mortgages and other loans payable
Scheduled Amortization
Remaining 2014	11,038
2015	44,701
2016	54,158
2017	61,063
2018	64,462
Thereafter	274,230
Total amortization of debt	509,652
Principal Repayments
Remaining 2014	146,250
2015	329,537
2016	338,762	[1]
2017	1,086,579	[1]
2018	0
Thereafter	3,927,404
Total principal repayments	5,828,532	[1]
Revolving credit facility
Amortization and Maturities of Long-term Debt [Abstract]
Remaining 2014	0
2015	0
2016	0
2017	0
2018	244,000
Thereafter	0
Total amortization of debt and principal repayments	244,000
Trust Preferred Securities
Amortization and Maturities of Long-term Debt [Abstract]
Remaining 2014	0
2015	0
2016	0
2017	0
2018	0
Thereafter	100,000
Total amortization of debt and principal repayments	100,000
Term Loan and Senior Unsecured Notes
Amortization and Maturities of Long-term Debt [Abstract]
Remaining 2014	0
2015	7
2016	255,308
2017	355,008
2018	250,000
Thereafter	1,233,000
Total amortization of debt and principal repayments	2,093,323
Joint Venture
Amortization and Maturities of Long-term Debt [Abstract]
Remaining 2014	2,454
2015	44,446
2016	564,269
2017	446,950
2018	28
Thereafter	353,580
Total amortization of debt and principal repayments	$ 1,411,727

[1] Principal repayments include the mortgages at 180 Maiden Lane and 2 Herald Center, which are included in liabilities related to assets held for sale.