Earnings Per Common Share (Unit) - Additional Information (Detail) - HOST HOTELS & RESORTS, INC. shares in Millions	9 Months Ended
Sep. 30, 2018 shares
Shares Subject To Mandatory Redemption By Settlement Terms [Line Items]
Common OP units outstanding	7.9
Number of common shares that would be outstanding if OP units were converted	8.1

The number of units or equivalent units outstanding for all classes.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-Subparagraph (SAB TOPIC 4.F)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant