Non-Controlling Interests - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2018 USD ($) Entity	Dec. 31, 2017 USD ($)
Minority Interest [Line Items]
Number of majority-owned partnerships that have third-party, non-controlling partners that have been consolidated | Entity	2
Non-controlling interests—other consolidated partnerships | $	$ 73	$ 29
HOST HOTELS & RESORTS L.P.
Minority Interest [Line Items]
OP units conversion basis	One common OP unit may be exchanged for 1.021494 shares of Host Inc
Shares issuable upon conversion of one OP unit	1.021494	1.021494