Summary of our Four Foreign Currency Purchase Contracts (Detail) In Millions	12 Months Ended	3 Months Ended	12 Months Ended
Dec. 31, 2010 USD ($)	Dec. 31, 2010 EUR (€)	Dec. 31, 2010 Forward currency purchase contracts USD ($)	Dec. 31, 2010 Forward currency purchase contracts EUR (€)	Dec. 31, 2009 Forward currency purchase contracts USD ($)	Dec. 31, 2010 Forward currency purchase contracts Group 1 USD ($)	Dec. 31, 2010 Forward currency purchase contracts Group 1 EUR (€)	Dec. 31, 2009 Forward currency purchase contracts Group 1 USD ($)	Sep. 30, 2010 Forward currency purchase contracts Group 4 USD ($)	Sep. 30, 2010 Forward currency purchase contracts Group 4 EUR (€)	Dec. 31, 2010 Forward currency purchase contracts Group 4 USD ($)	Dec. 31, 2010 Forward currency purchase contracts Group 4 EUR (€)	Dec. 31, 2010 Forward currency purchase contracts Group 2 USD ($)	Dec. 31, 2010 Forward currency purchase contracts Group 2 EUR (€)	Dec. 31, 2009 Forward currency purchase contracts Group 2 USD ($)	Dec. 31, 2010 Forward currency purchase contracts Group 3 USD ($)	Dec. 31, 2010 Forward currency purchase contracts Group 3 EUR (€)	Dec. 31, 2009 Forward currency purchase contracts Group 3 USD ($)	Dec. 31, 2010 Group 1	Dec. 31, 2010 Group 2	Dec. 31, 2010 Group 3	Dec. 31, 2010 Group 4
Fair Value			$ 6.9		$ 1.7	$ 2.8		$ (0.1)			$ (1.0)		$ 2.2		$ 0.7	$ 2.9		$ 1.1
Change Fair Value			5.2		(4.4)	2.9		(1.8)			(1.0)		1.5		(1.2)	1.8		(1.4)
Transaction Date																			Feb. 28, 2008	Feb. 28, 2008	May 31, 2008	Jul. 31, 2010
Forward Purchase Date											Oct. 01, 2014	Oct. 01, 2014							Aug. 31, 2011	Feb. 28, 2013	May 31, 2014	Oct. 31, 2014
Transaction Amount	$ 114	€ 80	$ 114	€ 80		$ 43	€ 30		$ 26	€ 20	$ 26	€ 20	$ 22	€ 15		$ 23	€ 15

Derivative, Transaction Date

Name:	hst_DerivativeTransactionDate
Namespace Prefix:	hst
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ Details

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

- Definition

The date the derivative matures.

+ Details

Name:	us-gaap_DerivativeMaturityDate
Namespace Prefix:	us-gaap
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	instant

- Definition

Fair value as of the balance sheet date of all derivatives designated as foreign currency fair value hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 10

+ Details

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

- Definition

Amount of gain (loss) from the increase (decrease) in fair value of foreign currency derivatives and nonderivative instruments designated as fair value hedging instruments which were recognized in earnings, net of offsets by the gain (loss) on the hedged item to the extent that the fair value hedge was determined to be effective.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 45
-Subparagraph a(1)

+ Details

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