Condensed Consolidated Financial Statements, Impacts of Adopting ASC 606 (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Condensed Consolidated Statements of Operations [Abstract]
Revenues		$ 668.2	$ 579.1	$ 1,287.7	$ 1,060.8
Cost of sales		418.9	363.2	806.6	670.3
Provision (benefit) for income taxes		17.2	(43.9)	40.7	(45.6)
Net income (loss)		60.3	$ (146.3)	102.7	$ (153.2)
Assets [Abstract]
Inventories		555.6		555.6		$ 494.5
Other current assets		56.7		56.7		39.5
Liabilities and Stockholders' Equity [Abstract]
Accrued liabilities		252.6		252.6		271.2
Accumulated deficit		(475.4)		(475.4)		$ (577.8)
Adjustments [Member] | ASC 606 [Member]
Condensed Consolidated Statements of Operations [Abstract]
Revenues		(5.5)		(9.4)
Cost of sales		(3.1)		(5.8)
Provision (benefit) for income taxes		(0.7)		(1.0)
Net income (loss)		(1.7)		(2.6)
Assets [Abstract]
Inventories		5.8		5.8
Other current assets	[1]	(5.8)		(5.8)
Liabilities and Stockholders' Equity [Abstract]
Accrued liabilities		2.6		2.6
Accumulated deficit		(2.6)		(2.6)
Balance Without Adoption of ASC 606 [Member] | ASC 606 [Member]
Condensed Consolidated Statements of Operations [Abstract]
Revenues		662.7		1,278.3
Cost of sales		415.8		800.8
Provision (benefit) for income taxes		16.5		39.7
Net income (loss)		58.6		100.1
Assets [Abstract]
Inventories		561.4		561.4
Other current assets		50.9		50.9
Liabilities and Stockholders' Equity [Abstract]
Accrued liabilities		255.2		255.2
Accumulated deficit		$ (478.0)		$ (478.0)

[1] Adjustment represents "Contract asset." 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.