Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions	1 Months Ended	12 Months Ended
	Apr. 30, 2020 Hotel	Dec. 31, 2020 USD ($) Hotel Entity	Dec. 31, 2019 USD ($) Property	Dec. 31, 2018 USD ($) Property
Significant Accounting Policies [Line Items]
Draws on credit facility		$ 2,245		$ 360
Total assets of VIE		12,890	$ 12,305
Liabilities of VIE		6,456	4,838
Advances to and investments in affiliates		$ 21	$ 56
Percentage of property revenue allocated for renewal and replacement capital expenditures		5.00%
Number of impaired assets | Property			1	4
Impairment charges			$ 14	$ 260
Number of majority-owned partnerships that have third-party, non-controlling ownership interests that have been consolidated | Entity		2
Non-redeemable non-controlling interests-other consolidated partnerships		$ 5	6
Net income (loss) attributable to non-controlling interests		(1)	2	52
Net income (loss)		$ (8)	10	12
Percentage greater than threshold of income tax examination minimum likelihood of tax benefits being realized upon settlement		50.00%
Net loss related to sale of assets, previously recognized in foreign currency translation and other comprehensive income (loss) of unconsolidated affiliates, reclassified		$ (1)	(4)	(13)
RSU Awards | Vesting over one-year Period
Significant Accounting Policies [Line Items]
Equity award vesting period		1 year
RSU Awards | Vesting over two-year Period
Significant Accounting Policies [Line Items]
Equity award vesting period		2 years
RSU Awards | Vesting over three-year Period
Significant Accounting Policies [Line Items]
Equity award vesting period		3 years
Property, Plant and Equipment, Other Types
Significant Accounting Policies [Line Items]
Estimated useful lives		3 years
HOST HOTELS & RESORTS L.P.
Significant Accounting Policies [Line Items]
Draws on credit facility		$ 2,245		360
Total assets of VIE		12,890	12,305
Liabilities of VIE		$ 6,456	$ 4,838
OP units conversion basis		one OP unit may be exchanged for 1.021494 shares of Host Inc. common stock) valued at the market price of Host Inc.
Shares issuable upon conversion of one OP unit		1.021494	1.021494
Net loss related to sale of assets, previously recognized in foreign currency translation and other comprehensive income (loss) of unconsolidated affiliates, reclassified		$ (1)	$ (4)	$ (13)
Houston Airport Marriott at George Bush Intercontinental | Variable Interest Entities
Significant Accounting Policies [Line Items]
Total assets of VIE		59
Liabilities of VIE		$ 28
Houston Airport Marriott at George Bush Intercontinental | General Partner
Significant Accounting Policies [Line Items]
General partner and limited partner interest		85.00%
Philadelphia Marriott Downtown | Variable Interest Entities Not Primary Beneficiary
Significant Accounting Policies [Line Items]
Advances to and investments in affiliates		$ (7)
Philadelphia Marriott Downtown | Limited Partner Interest
Significant Accounting Policies [Line Items]
General partner and limited partner interest		11.00%
COVID - 19
Significant Accounting Policies [Line Items]
Number of hotels suspends operations | Hotel	35	4
COVID - 19 | Revolving Credit Facility
Significant Accounting Policies [Line Items]
Draws on credit facility		$ 1,500
Host L.P.
Significant Accounting Policies [Line Items]
Investment ownership percentage		99.00%