Debt Instrument, Covenant, Availability plus Suppressed Availability

No definition available.

Name:	m_DebtInstrumentCovenantAvailabilityplusSuppressedAvailability
Namespace Prefix:	m_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt Instrument, Covenant, Percent of Loan Cap

+ References

No definition available.

+ Details

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Namespace Prefix:	m_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument, Coverage Ratio

+ References

No definition available.

+ Details

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Namespace Prefix:	m_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument, Liquidation Percentage

+ References

No definition available.

+ Details

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Namespace Prefix:	m_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument, Liquidation Percentage, Upon Satisfaction of Certain Conditions

+ References

No definition available.

+ Details

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Namespace Prefix:	m_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt subject to consent offer

+ References

No definition available.

+ Details

Name:	m_DebtSubjectToConsentOffer
Namespace Prefix:	m_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line of Credit Facility, Additional Borrowing Capacity Available

+ References

No definition available.

+ Details

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Namespace Prefix:	m_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-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=119400593&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-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 4: http://fasb.org/us-gaap/role/ref/legacyRef
-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

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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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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

+ Details

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

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Financing Activities - Narrative (Details) - USD ($)		3 Months Ended	6 Months Ended
Financing Activities - Narrative (Details) - USD ($)	Jun. 08, 2020	Aug. 01, 2020	Aug. 01, 2020	Aug. 03, 2019	Jun. 30, 2020
Line of Credit Facility, Maximum Borrowing Capacity		$ 1,500,000,000	$ 1,500,000,000
Proceeds from Issuance of Debt			$ 2,780,000,000	$ 0
New 2024 Notes
Interest rate stated percentage		6.65%	6.65%
Long-term Debt, Gross		$ 81,000,000	$ 81,000,000
Old 2024 Notes
Interest rate stated percentage					6.65%
New 2028 Notes
Interest rate stated percentage		6.70%	6.70%
Long-term Debt, Gross		$ 74,000,000	$ 74,000,000
Old 2028 Notes
Interest rate stated percentage					6.70%
New 2029 Notes
Interest rate stated percentage		8.75%	8.75%
Long-term Debt, Gross		$ 13,000,000	$ 13,000,000
Old 2029 Notes
Interest rate stated percentage					8.75%
New 2030 Notes
Interest rate stated percentage		7.875%	7.875%
Long-term Debt, Gross		$ 5,000,000	$ 5,000,000
Old 2030 Notes
Interest rate stated percentage					7.875%
New 2032 Notes
Interest rate stated percentage		6.90%	6.90%
Long-term Debt, Gross		$ 5,000,000	$ 5,000,000
Old 2032 Notes
Interest rate stated percentage					6.90%
New 2034 Notes
Interest rate stated percentage		6.70%	6.70%
Long-term Debt, Gross		$ 183,000,000	$ 183,000,000
Old 2034 Notes
Interest rate stated percentage					6.70%
Revolving Credit Facility [Member]
Proceeds from Lines of Credit			1,500,000,000
Revolving Credit Facility [Member] \| April 30, 2021 or After
Percent of loan cap	10.00%
Availability plus suppressed availability	$ 250,000,000
Revolving Credit Facility [Member] \| Prior to April 30, 2021
Percent of loan cap	10.00%
Availability plus suppressed availability	$ 250,000,000
ABL Borrower \| Revolving Credit Facility [Member]
Additional borrowing capacity available	$ 750,000,000
Liquidation percentage	80.00%
Liquidation percentage, upon satisfaction of certain conditions	90.00%
ABL Borrower \| Revolving Credit Facility [Member] \| Revolving ABL Facility
Line of Credit Facility, Maximum Borrowing Capacity		2,926,000,000	2,926,000,000
ABL Borrower \| Revolving Credit Facility [Member] \| Bridge Facility
Line of Credit Facility, Maximum Borrowing Capacity	$ 300,000,000
Senior Notes
Face amount	$ 1,300,000,000
Interest rate stated percentage	8.375%
Old 2024 Notes
Long-term Debt, Gross		41,000,000	41,000,000
Debt subject to consent offer		85,000,000
Old 2028 Notes
Long-term Debt, Gross		29,000,000	29,000,000
Debt subject to consent offer		77,000,000
Old 2029 Notes
Debt subject to consent offer		13,000,000
Old 2030 Notes
Long-term Debt, Gross		5,000,000	5,000,000
Debt subject to consent offer		5,000,000
Old 2032 Notes
Long-term Debt, Gross		12,000,000	12,000,000
Debt subject to consent offer		6,000,000
Old 2034 Notes
Long-term Debt, Gross		18,000,000	$ 18,000,000
Debt subject to consent offer		$ 185,000,000
Minimum
Current borrowing capacity	$ 25,000,000
Minimum \| ABL Borrower
Coverage ratio	1.00
Minimum \| ABL Borrower \| Revolving Credit Facility [Member] \| Prior to Step Down Date \| London Interbank Offered Rate (LIBOR)
Basis spread on variable rate	2.75%
Minimum \| ABL Borrower \| Revolving Credit Facility [Member] \| Prior to Step Down Date \| Base Rate
Basis spread on variable rate	1.75%
Minimum \| ABL Borrower \| Revolving Credit Facility [Member] \| After Step Down Date \| London Interbank Offered Rate (LIBOR)
Basis spread on variable rate	2.25%
Minimum \| ABL Borrower \| Revolving Credit Facility [Member] \| After Step Down Date \| Base Rate
Basis spread on variable rate	1.25%
Maximum \| ABL Borrower
Coverage ratio	1.00
Maximum \| ABL Borrower \| Revolving Credit Facility [Member] \| Prior to Step Down Date \| London Interbank Offered Rate (LIBOR)
Basis spread on variable rate	3.00%
Maximum \| ABL Borrower \| Revolving Credit Facility [Member] \| Prior to Step Down Date \| Base Rate
Basis spread on variable rate	2.00%
Maximum \| ABL Borrower \| Revolving Credit Facility [Member] \| After Step Down Date \| London Interbank Offered Rate (LIBOR)
Basis spread on variable rate	2.50%
Maximum \| ABL Borrower \| Revolving Credit Facility [Member] \| After Step Down Date \| Base Rate
Basis spread on variable rate	1.50%