Condensed Consolidated Financial Statements (Details) $ in Millions				3 Months Ended
		Nov. 15, 2017 shares	May 31, 2017 shares	Mar. 31, 2018 USD ($) Contract	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Condensed Consolidated Statements of Operations [Abstract]
Revenues				$ 619.6	$ 481.7
Cost of sales				387.7	307.1
Provision (benefit) for income taxes				23.4	(1.6)
Net income (loss)				42.4	(7.0)
Assets [Abstract]
Inventories				567.2		$ 494.5
Other current assets				50.8		39.5
Liabilities and Stockholders' Equity [Abstract]
Accrued liabilities				305.4		271.2
Accumulated deficit				(535.7)		(577.8)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Selling and administrative expenses				$ 106.9	102.3
Interest Rate Swap [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of contracts | Contract				12
Interest Rate Swap [Member] | LIBOR [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Long-term debt hedged				$ 1,125.0
ASU 2017-07 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Selling and administrative expenses					(0.1)
Other income, net					$ 0.1
ASU 2017-12 [Member] | Interest Rate Swap [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of contracts | Contract				12
ASU 2017-12 [Member] | Interest Rate Swap [Member] | LIBOR [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Long-term debt hedged				$ 1,125.0
Adjustments [Member] | ASC 606 [Member]
Condensed Consolidated Statements of Operations [Abstract]
Revenues				(3.9)
Cost of sales				(2.7)
Provision (benefit) for income taxes				(0.3)
Net income (loss)				(0.9)
Assets [Abstract]
Inventories				2.7
Other current assets	[1]			(2.7)
Liabilities and Stockholders' Equity [Abstract]
Accrued liabilities				0.9
Accumulated deficit				(0.9)
Balance Without Adoption of ASC 606 [Member] | ASC 606 [Member]
Condensed Consolidated Statements of Operations [Abstract]
Revenues				615.7
Cost of sales				385.0
Provision (benefit) for income taxes				23.1
Net income (loss)				41.5
Assets [Abstract]
Inventories				569.9
Other current assets				48.1
Liabilities and Stockholders' Equity [Abstract]
Accrued liabilities				306.3
Accumulated deficit				(536.6)
Common Stock [Member]
Subsidiary, Sale of Stock [Line Items]
Stock sold in initial public offering (in shares) | shares			47,495,000
Common Stock [Member] | Kohlberg Kravis Roberts & Co. L.P [Member]
Subsidiary, Sale of Stock [Line Items]
Stock sold in initial public offering (in shares) | shares		25,300,000
Accumulated Deficit [Member]
Condensed Consolidated Statements of Operations [Abstract]
Net income (loss)				$ 42.4
Accumulated Deficit [Member] | ASU 2017-12 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment						(0.3)
Accumulated Other Comprehensive Loss [Member] | ASU 2017-12 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment	[2]					$ 0.3

[1] Adjustment represents "Contract assets". See Note 12 "Revenue from Contracts with Customers" for an explanation of the Contract assets account included in "Other Current assets" in the Condensed Consolidated Balance Sheets.

[2] All amounts are net of tax. Amounts in parentheses indicate debits.