Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating Activities
Net income	$ 27.8	$ 18.1
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	14.4	15.2
Amortization of debt discount and deferred financing costs	0.4	1.5
Stock-based compensation	(0.9)	2.8
Retirement benefits, net	(6.6)	(2.5)
Loss on debt	0.0	9.1
Other, net	0.5	(0.3)
Changes in assets and liabilities:
Accounts receivable	(82.8)	(130.7)
Contract assets	(17.8)	(11.9)
Other current assets	5.9	14.1
Recoverable environmental remediation costs	5.5	3.9
Other noncurrent assets	6.8	2.3
Accounts payable	(19.0)	(27.4)
Contract liabilities	0.2	29.9
Other current liabilities	45.3	14.6
Deferred income taxes	(45.8)	(3.0)
Reserves for environmental remediation costs	(2.7)	(5.3)
Other noncurrent liabilities and other	(6.2)	0.2
Net Cash Used in Operating Activities	(75.0)	(69.4)
Investing Activities
Purchases of marketable securities	0.0	(1.9)
Capital expenditures	(2.2)	(3.8)
Net Cash Used in Investing Activities	(2.2)	(5.7)
Financing Activities
Dividend payments	(1.2)	(428.5)
Debt repayments	(7.1)	(142.4)
Repurchase of shares for withholding taxes and option costs under equity plans	(4.3)	(4.0)
Proceeds from shares issued under equity plans	0.3	4.2
Net Cash Used in Financing Activities	(12.3)	(570.7)
Net Decrease in Cash, Cash Equivalents and Restricted Cash	(89.5)	(645.8)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	703.4	1,152.5
Cash, Cash Equivalents and Restricted Cash at End of Period	613.9	506.7
Supplemental disclosures of cash flow information
Cash paid for interest	$ 2.6	$ 2.7