Long-Term Debt (Detail) - USD ($)	Mar. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
$2,000 Credit Facility	$ 0	$ 0
Other	111,000,000	113,000,000
Balance at March 31, 2016	4,159,000,000	4,107,000,000
Less: Current portion of long-term debt	(300,000,000)	(300,000,000)
Long-term debt, noncurrent	3,859,000,000	3,807,000,000
Multicurrency revolving credit agreement, aggregate borrowings	2,000,000,000	2,000,000,000
Series H, Senior Notes 6.2% Due June 15, 2016
Debt Instrument [Line Items]
Senior Notes	289,000,000	289,000,000
Series I, Senior Notes 6.4% Due June 15, 2017
Debt Instrument [Line Items]
Senior Notes	293,000,000	293,000,000
Series K, Senior Notes 3.0% Due March 1, 2019
Debt Instrument [Line Items]
Senior Notes	596,000,000	595,000,000
Series L, Senior Notes 3.3% Due September 15, 2022
Debt Instrument [Line Items]
Senior Notes	348,000,000	348,000,000
Series M, Senior Notes 3.4% Due October 15, 2020
Debt Instrument [Line Items]
Senior Notes	347,000,000	347,000,000
Series N, Senior Notes 3.1% Due October 15, 2021
Debt Instrument [Line Items]
Senior Notes	395,000,000	395,000,000
Series O, Senior Notes 2.9% Due March 1, 2021
Debt Instrument [Line Items]
Senior Notes	446,000,000	446,000,000
Series P, Senior Notes 3.8% Due October 1, 2025
Debt Instrument [Line Items]
Senior Notes	$ 343,000,000	$ 343,000,000
Senior Notes \| Series H, Senior Notes 6.2% Due June 15, 2016
Debt Instrument [Line Items]
Debt instrument, stated interest rate	6.20%	6.20%
Senior Notes, face amount	$ 289,000,000	$ 289,000,000
Senior Notes, effective interest rate	6.30%	6.30%
Senior Notes \| Series I, Senior Notes 6.4% Due June 15, 2017
Debt Instrument [Line Items]
Debt instrument, stated interest rate	6.40%	6.40%
Senior Notes, face amount	$ 293,000,000	$ 293,000,000
Senior Notes, effective interest rate	6.50%	6.50%
Senior Notes \| Series K, Senior Notes 3.0% Due March 1, 2019
Debt Instrument [Line Items]
Debt instrument, stated interest rate	3.00%	3.00%
Senior Notes, face amount	$ 600,000,000	$ 600,000,000
Senior Notes, effective interest rate	4.40%	4.40%
Senior Notes \| Series L, Senior Notes 3.3% Due September 15, 2022
Debt Instrument [Line Items]
Debt instrument, stated interest rate	3.30%	3.30%
Senior Notes, face amount	$ 350,000,000	$ 350,000,000
Senior Notes, effective interest rate	3.40%	3.40%
Senior Notes \| Series M, Senior Notes 3.4% Due October 15, 2020
Debt Instrument [Line Items]
Debt instrument, stated interest rate	3.40%	3.40%
Senior Notes, face amount	$ 350,000,000	$ 350,000,000
Senior Notes, effective interest rate	3.60%	3.60%
Senior Notes \| Series N, Senior Notes 3.1% Due October 15, 2021
Debt Instrument [Line Items]
Debt instrument, stated interest rate	3.10%	3.10%
Senior Notes, face amount	$ 400,000,000	$ 400,000,000
Senior Notes, effective interest rate	3.40%	3.40%
Senior Notes \| Series O, Senior Notes 2.9% Due March 1, 2021
Debt Instrument [Line Items]
Debt instrument, stated interest rate	2.875%	2.875%
Senior Notes, face amount	$ 450,000,000	$ 450,000,000
Senior Notes, effective interest rate	3.10%	3.10%
Senior Notes \| Series P, Senior Notes 3.8% Due October 1, 2025
Debt Instrument [Line Items]
Debt instrument, stated interest rate	3.80%	3.80%
Senior Notes, face amount	$ 350,000,000	$ 350,000,000
Senior Notes, effective interest rate	4.00%	4.00%
Commercial Paper
Debt Instrument [Line Items]
Commercial paper, average interest rate of 0.8% at March 31, 2016	$ 991,000,000	$ 938,000,000
Long-term debt, average interest rate	0.80%

Long-term Debt and Capital Lease Obligations, Other

No definition available.

Name:	mar_LongtermDebtandCapitalLeaseObligationsOther
Namespace Prefix:	mar_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of long-term unsecured obligations issued by corporations and other borrowers to investors (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

+ References

+ Details

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

- Definition

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13,16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

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

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
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_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 20, 22
-Article 5

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

Amount of long-term debt and capital lease obligation due after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 6
-Section H

+ Details

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

- Definition

Amount of long-term debt and capital leases due within one year or the normal operating cycle, if longer.

+ References

+ Details

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

- Definition

Weighted average interest rate of long-term debt outstanding.

+ References

No definition available.

+ Details

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

- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16(a))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=mar_SeriesHSeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mar_SeriesISeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mar_SeriesKSeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mar_SeriesLSeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mar_SeriesMSeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mar_SeriesNSeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mar_SeriesOSeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mar_SeriesPSeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_CommercialPaperMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: