Consolidated Statements of Cash Flows - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Nov. 30, 2015
Operating Activities
Net (loss) income	$ 7.0	$ (9.2)	$ 18.0	$ (16.2)
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization	5.1	72.6	64.9	65.1
Amortization of debt discount and deferred financing costs	0.2	8.5	2.3	2.7
Stock-based compensation	(0.4)	22.0	12.9	8.6
Retirement benefits, net	5.4	(8.2)	30.5	61.4
Loss on debt repurchased	0.0	0.0	34.4	1.9
Other, net	0.0	0.7	0.6	(0.3)
Changes in assets and liabilities, net of effects from acquisition:
Accounts receivable	2.0	(67.6)	33.1	(1.0)
Inventories	1.3	48.6	(28.9)	(19.5)
Other current assets, net	(4.8)	13.0	(23.8)	(25.7)
Recoverable from the U.S. government and other third parties for environmental remediation costs	3.2	8.7	(32.6)	(127.8)
Other noncurrent assets	(0.1)	(31.4)	(12.6)	10.2
Accounts payable	(41.0)	1.6	27.0	(5.1)
Advance payments on contracts	27.2	16.0	(9.1)	6.3
Other current liabilities	5.6	8.2	(37.4)	(18.8)
Deferred income taxes	(7.1)	125.7	4.8	(27.6)
Reserves for environmental remediation costs	(3.8)	(8.3)	47.4	140.1
Other noncurrent liabilities and other	0.3	11.9	27.2	13.3
Net Cash Provided by Operating Activities	0.1	212.8	158.7	67.6
Investing Activities
Purchases of marketable securities		(24.0)	0.0	0.0
Sale of marketable securities		4.0	0.0	0.0
Purchase of Coleman Aerospace	0.0	(17.0)	0.0	0.0
Proceeds from sale of technology	0.0	0.0	0.5	1.0
Capital expenditures	(1.2)	(29.4)	(47.6)	(36.8)
Net Cash Used in Investing Activities	(1.2)	(66.4)	(47.1)	(35.8)
Financing Activities
Proceeds from issuance of debt	0.0	0.0	800.0	0.0
Debt issuance costs including equity component of convertible debt	0.0	0.0	(9.5)	0.0
Debt repayments/repurchases	(1.3)	(20.0)	(700.6)	(81.2)
Proceeds from shares issued under equity plans, net	0.0	4.5	4.2	1.3
Repurchase of shares for option cost and to satisfy tax withholding obligations	(0.2)	(6.2)	(3.9)	(6.7)
Net Cash (Used in) Provided by Financing Activities	(1.5)	(21.7)	90.2	(86.6)
Net Increase (Decrease) in Cash and Cash Equivalents	(2.6)	124.7	201.8	(54.8)
Cash and Cash Equivalents at Beginning of Period	211.1	410.3	208.5	265.9
Cash and Cash Equivalents at End of Period	208.5	535.0	410.3	211.1
Supplemental disclosures of cash flow information
Cash paid for interest	2.7	22.2	39.0	49.3
Cash paid for income taxes	0.0	3.0	31.2	27.9
Cash refund for income taxes	0.0	22.9	0.1	0.0
Capital leases	0.0	0.9	0.0	0.0
Conversion of debt to common stock	$ 0.0	$ 35.6	$ 49.0	$ 49.0