Debt - Summary of Outstanding Debt (Details) - USD ($) $ in Thousands		3 Months Ended
	Jan. 19, 2017	Mar. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Notes and mortgages payable, Interest Rate		3.60%
Notes and mortgages payable		$ 3,526,279	$ 3,408,179
Credit Facility		200,000	230,000
Less: deferred financing costs		(48,481)	(43,281)
Total notes and mortgages payable, net		$ 3,477,798	3,364,898
Credit Facility With Variable Rate [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maturity date of debt		2018-11
Interest Rate		2.23%
Credit Facility		$ 200,000	230,000
Credit Facility With Variable Rate [Member] | London Interbank Offered Rate (LIBOR) | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Fixed/Variable Rate		1.25%
1633 Broadway [Member]
Debt Instrument [Line Items]
Notes and mortgages payable, Interest Rate		3.52%
Notes and mortgages payable		$ 1,030,100	1,013,544
1633 Broadway [Member] | Mortgages and Notes Payable with Fixed Rate [Member]
Debt Instrument [Line Items]
Maturity date of debt		2022-12
Notes and mortgages payable, Interest Rate		3.54%
Notes and mortgages payable		$ 1,000,000	1,000,000
1633 Broadway [Member] | Mortgages and Notes Payable with Variable Rate [Member]
Debt Instrument [Line Items]
Maturity date of debt		2022-12
Notes and mortgages payable, Interest Rate		2.73%
Notes and mortgages payable		$ 30,100	13,544
1633 Broadway [Member] | Mortgages and Notes Payable with Variable Rate [Member] | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Fixed/Variable Rate		1.75%
One Market Plaza [Member]
Debt Instrument [Line Items]
Notes and mortgages payable, Interest Rate		4.03%
Notes and mortgages payable		$ 975,000	872,960
One Market Plaza [Member] | Mortgages and Notes Payable with Fixed Rate [Member]
Debt Instrument [Line Items]
Maturity date of debt	2024-02	2024-02
Notes and mortgages payable, Interest Rate	4.03%	4.03%
Notes and mortgages payable		$ 975,000	860,546
One Market Plaza [Member] | Mortgages and Notes Payable with Variable Rate [Member]
Debt Instrument [Line Items]
Notes and mortgages payable			12,414
1301 Avenue of Americas [Member]
Debt Instrument [Line Items]
Notes and mortgages payable, Interest Rate		2.87%
Notes and mortgages payable		$ 850,000	850,000
1301 Avenue of Americas [Member] | Mortgages and Notes Payable with Fixed Rate [Member]
Debt Instrument [Line Items]
Maturity date of debt		2021-11
Notes and mortgages payable, Interest Rate		3.05%
Notes and mortgages payable		$ 500,000	500,000
1301 Avenue of Americas [Member] | Mortgages and Notes Payable with Variable Rate [Member]
Debt Instrument [Line Items]
Maturity date of debt		2021-11
Notes and mortgages payable, Interest Rate		2.61%
Notes and mortgages payable		$ 350,000	350,000
1301 Avenue of Americas [Member] | Mortgages and Notes Payable with Variable Rate [Member] | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Fixed/Variable Rate		1.80%
31 West 52nd Street [Member] | Mortgages and Notes Payable with Fixed Rate [Member]
Debt Instrument [Line Items]
Maturity date of debt		2026-05
Notes and mortgages payable, Interest Rate		3.80%
Notes and mortgages payable		$ 500,000	500,000
1899 Pennsylvania Avenue [Member] | Mortgages and Notes Payable with Fixed Rate [Member]
Debt Instrument [Line Items]
Maturity date of debt		2020-11
Notes and mortgages payable, Interest Rate		4.88%
Notes and mortgages payable		$ 87,179	87,675
Liberty Place [Member] | Mortgages and Notes Payable with Fixed Rate [Member]
Debt Instrument [Line Items]
Maturity date of debt		2018-06
Notes and mortgages payable, Interest Rate		4.50%
Notes and mortgages payable		$ 84,000	$ 84,000