Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of period		$ 42.8	$ 28.0		$ 33.0
Charges to cost and expense		50.2	24.6		2.2
Other additions		0.0	1.0		10.3
(Deductions)		(9.4)	(10.8)		(17.5)
Balance at end of period		83.6	42.8		28.0
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of period		8.4	7.7		13.9
Charges to cost and expense	[1]	2.6	2.9		2.1
Other additions		0.0	0.0		0.0
(Deductions)	[2]	(2.8)	(2.2)		(8.3)
Balance at end of period		8.2	8.4		7.7
Costs and Earnings in Excess of Billings Allowance [Member]
Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of period		9.5	6.9		12.5
Charges to cost and expense	[1]	22.3	9.9		0.0
Other additions		0.0	0.0		0.0
(Deductions)	[2]	(4.6)	(7.3)		(5.6)
Balance at end of period		27.2	9.5		6.9
Inventory Valuation Reserve [Member]
Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of period		3.5	2.8		6.4
Charges to cost and expense	[3]	6.2	2.0		0.0
Other additions		0.0	0.0		0.0
(Deductions)	[4]	(2.0)	(1.3)		(3.6)
Balance at end of period		7.7	3.5		2.8
Valuation Allowance for Deferred Tax Assets [Member]
Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of period		21.4	10.6		0.2
Charges to cost and expense	[5]	19.1	9.8		0.1
Other additions		0.0	1.0	[6]	10.3	[6]
(Deductions)		0.0	0.0		0.0
Balance at end of period		$ 40.5	$ 21.4		$ 10.6

[1] Provisions for doubtful accounts and costs and earnings in excess of billings.

[2] Write-offs and reversals of uncollectible accounts receivable and non-billable costs and earnings in excess of billings.

[3] Provision for inventory obsolescence.

[4] Inventory write-offs.

[5] Additions related to federal, foreign, and state attributes.

[6] Additions related to unrealized gains and losses.