Leases - Additional Information (Detail) $ in Millions	3 Months Ended
Mar. 31, 2019 USD ($) GroundLease Office
Lessee Lease Description [Line Items]
Number of ground leases \| GroundLease	25
Financial leases \| $	$ 1
Ground Leases
Lessee Lease Description [Line Items]
Percentage of 2019 minimum lease payments	80.00%
Percentage of total future minimum lease payments	99.00%
Ground Leases \| Minimum
Lessee Lease Description [Line Items]
Discount rates	4.30%
Ground Leases \| Minimum \| IBR
Lessee Lease Description [Line Items]
LIBOR swap rates, terms used to calculate IBR	1 year
Ground Leases \| Maximum
Lessee Lease Description [Line Items]
Discount rates	5.70%
Ground Leases \| Maximum \| IBR
Lessee Lease Description [Line Items]
LIBOR swap rates, terms used to calculate IBR	50 years
Office Leases \| Bethesda
Lessee Lease Description [Line Items]
Lease expiration date	2022
Office Leases \| Miami
Lessee Lease Description [Line Items]
Lease expiration date	2022
Office Leases \| San Diego
Lessee Lease Description [Line Items]
Lease expiration date	2021
Office Leases \| Miami and San Diego
Lessee Lease Description [Line Items]
Number of satellite offices \| Office	2

Lease expiration year.

No definition available.

Name:	hst_LeaseExpirationYear
Namespace Prefix:	hst_
Data Type:	us-types:gYearListItemType
Balance Type:	na
Period Type:	duration

- Definition

London Interbank Offered Rate swap rates terms used to calculate incremental borrowing rate.

+ References

No definition available.

+ Details

Name:	hst_LondonInterbankOfferedRateSwapRatesTermsUsedToCalculateIncrementalBorrowingRate
Namespace Prefix:	hst_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of satellite offices.

+ References

No definition available.

+ Details

Name:	hst_NumberOfSatelliteOffices
Namespace Prefix:	hst_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of current fiscal year minimum lease payments.

+ References

No definition available.

+ Details

Name:	hst_PercentageOfCurrentFiscalYearMinimumLeasePayments
Namespace Prefix:	hst_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of future minimum lease payments.

+ References

No definition available.

+ Details

Name:	hst_PercentageOfFutureMinimumLeasePayments
Namespace Prefix:	hst_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Present value of lessee's discounted obligation for lease payments from finance lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918701-209980

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977

+ Details

Name:	us-gaap_FinanceLeaseLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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.

+ Details

Name:	us-gaap_LesseeLeaseDescriptionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Discount rate used by lessee to determine present value of operating lease payments.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918673-209980

+ Details

Name:	us-gaap_LesseeOperatingLeaseDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of separate real estate development properties located on land subject to ground leases.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfPropertiesSubjectToGroundLeases
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	hst_TypesOfLeasesAxis=hst_GroundLeasesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=hst_IncrementalBorrowingRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	hst_TypesOfLeasesAxis=hst_OfficeLeasesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=hst_BethesdaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=hst_MiamiMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=hst_SanDiegoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=hst_MiamiAndSanDiegoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: