Debt - Summary of Outstanding Debt (Parenthetical) (Details) - USD ($) $ in Billions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Credit Facility With Variable Rate [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Repayments of Long-term Lines of Credit	$ 1.0	$ 1.0
1633 Broadway [Member]
Debt Instrument [Line Items]
Ownership interest rate of property	90.00%	90.00%
One Market Plaza [Member]
Debt Instrument [Line Items]
Ownership interest rate of property	49.00%	49.00%
300 Mission Street [Member]
Debt Instrument [Line Items]
Ownership interest rate of property	31.10%	31.10%

The cash outflow for the settlement of obligation drawn from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585

Name:	us-gaap_RepaymentsOfLongTermLinesOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration