Debt - Summary of Outstanding Debt (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Notes and mortgages payable, Interest Rate	3.69%
Notes and mortgages payable	$ 3,603,000	$ 3,599,800
Credit Facility	0	0
Less: deferred financing costs	(26,266)	(32,883)
Total notes and mortgages payable, net	$ 3,576,734	3,566,917
Credit Facility With Variable Rate [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maturity date of debt	2022-01
Credit Facility With Variable Rate [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Fixed/Variable Rate	1.15%
1633 Broadway [Member]
Debt Instrument [Line Items]
Notes and mortgages payable, Interest Rate	3.55%
Notes and mortgages payable	$ 1,050,000	1,046,800
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	3.85%
Notes and mortgages payable	$ 50,000	46,800
1633 Broadway [Member] \| Mortgages and Notes Payable with Variable Rate [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Fixed/Variable Rate	1.75%
One Market Plaza [Member] \| Mortgages and Notes Payable with Fixed Rate [Member]
Debt Instrument [Line Items]
Maturity date of debt	2024-02
Notes and mortgages payable, Interest Rate	4.03%
Notes and mortgages payable	$ 975,000	975,000
1301 Avenue of Americas [Member]
Debt Instrument [Line Items]
Notes and mortgages payable, Interest Rate	3.41%
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	3.93%
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) [Member]
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
300 Mission Street [Member] \| Mortgages and Notes Payable with Fixed Rate [Member]
Debt Instrument [Line Items]
Maturity date of debt	2021-10
Notes and mortgages payable, Interest Rate	3.65%
Notes and mortgages payable	$ 228,000	$ 228,000

Debt instrument, maturity date in month and year.

No definition available.

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- Definition

Notes and loans payable, net.

+ References

No definition available.

+ Details

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
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- Definition

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.

+ References

No definition available.

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- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

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- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of all notes and loans payable (with maturities initially due after one year or beyond the operating cycle if longer).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 210
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