The net cash outflow for a financial contract entered into to economically hedge foreign currency exposure.

Name:	hst_PurchasesOfForeignCurrencyContracts
Namespace Prefix:	hst
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Range of Dates Foreign Currency Exchange Rate Derivatives Mature

+ Details

Name:	hst_RangeOfDatesForeignCurrencyExchangeRateDerivativesMature
Namespace Prefix:	hst
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Range Of Derivative, Transaction Date

+ Details

Name:	hst_RangeOfDerivativeTransactionDate
Namespace Prefix:	hst
Data Type:	us-types:dateStringItemType
Balance Type:	na
Period Type:	duration

- 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.

+ Details

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Net fair value of all derivatives designated as hedges of net investment in foreign operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FIN39-1

-Paragraph 4

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 44C

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_NetInvestmentHedgeDerivativesAtFairValueNet
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Current period adjustment in other comprehensive income reflecting gains or losses on foreign currency transactions that are designated as, and are effective as, hedges of a net investment in a foreign entity, net of tax effect.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 44C

-Subparagraph b(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 52

-Paragraph 20

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 830

-SubTopic 30

-Section 45

-Paragraph 20

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6915805&loc=d3e32211-110900

+ Details

Name:	us-gaap_TranslationAdjustmentForNetInvestmentHedgeIncreaseDecreaseNetOfTax
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Foreign Currency Forwards Purchase Contracts (Detail) (Foreign currency forward purchase contracts) In Millions	1 Months Ended		3 Months Ended	9 Months Ended			1 Months Ended		3 Months Ended	9 Months Ended
	Jul. 15, 2011 Group 1 USD ($)	Jul. 15, 2011 Group 1 EUR (€)	Sep. 09, 2011 Group 1 EUR (€)	Sep. 09, 2011 Group 1 USD ($)	Sep. 10, 2010 Group 1 USD ($)	Dec. 31, 2010 Group 1 USD ($)	Jul. 29, 2011 Group 2 USD ($)	Jul. 29, 2011 Group 2 NZD	Sep. 09, 2011 Group 2 NZD	Sep. 09, 2011 Group 2 USD ($)
Derivative [Line Items]
Transaction Date Range			February 2008- July 2011						July 2011
Transaction Amount	$ 69	€ 50	€ 100	$ 140			$ 25	30	30	$ 25
Forward Purchase Date Range				October 2012-August 2015						August 2013
Fair Value				4.0		6.9				1.2
Change in Fair Value				$ (2.9)	$ 9.9					$ 1.2