Condensed Consolidated Statements of Operations - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Aug. 01, 2021	Aug. 02, 2020	Aug. 01, 2021	Aug. 02, 2020
Income Statement [Abstract]
Net sales		$ 1,297.6	$ 955.9	$ 2,352.7	$ 1,798.0
Cost of sales		972.4	725.3	1,770.7	1,368.2
Gross profit		325.2	230.6	582.0	429.8
Operating expenses:
Selling, general and administrative		191.8	136.8	345.7	273.8
Depreciation and amortization		33.6	34.3	67.4	67.8
Total operating expenses		225.4	171.1	413.1	341.6
Operating income		99.8	59.5	168.9	88.2
Interest expense		36.8	35.0	72.3	68.2
Loss on debt modification and extinguishment		50.4	0.0	50.4	0.0
Income before provision for income taxes		12.6	24.5	46.2	20.0
Provision for income taxes		3.1	6.4	9.3	5.1
Net income		9.5	18.1	36.9	14.9
Less: net loss attributable to non-controlling interests		(17.0)		(17.0)
Net income attributable to Core & Main, Inc.		$ 26.5	$ 18.1	$ 53.9	$ 14.9
Loss per share:
Basic (in dollars per share)	[1]	$ (0.14)		$ (0.14)
Diluted (in dollars per share)	[1]	$ (0.14)		$ (0.14)
Number of shares used in computing EPS
Basic (shares)	[1]	138,978,366		138,978,366
Diluted (shares)	[1]	138,978,366		138,978,366
Net sales [Extensible Enumeration]		us-gaap:ProductAndServiceOtherMember	us-gaap:ProductAndServiceOtherMember	us-gaap:ProductAndServiceOtherMember	us-gaap:ProductAndServiceOtherMember
Cost of sales [Extensible Enumeration]		us-gaap:ProductAndServiceOtherMember	us-gaap:ProductAndServiceOtherMember	us-gaap:ProductAndServiceOtherMember	us-gaap:ProductAndServiceOtherMember

[1] Represents basic and diluted loss per share of Class A common stock and weighted average shares of Class A common stock outstanding for the period from July 23, 2021 through August 1, 2021, the period following the Reorganization Transactions described in Note 1. See Note 12 for additional information on basic and diluted loss per share.