Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Current Assets
Cash and cash equivalents	$ 624.9	$ 1,149.5
Restricted cash	3.0	3.0
Marketable securities	9.8	7.0
Accounts receivable	85.2	75.6
Contract assets	327.7	288.6
Other current assets	121.3	136.5
Total Current Assets	1,171.9	1,660.2
Noncurrent Assets
Right-of-use assets	47.3	46.8
Property, plant and equipment, net	409.5	423.1
Recoverable environmental remediation costs	229.5	227.7
Deferred income taxes	69.7	81.1
Goodwill	161.4	161.4
Intangible assets	36.5	44.8
Other noncurrent assets	237.0	254.8
Total Noncurrent Assets	1,190.9	1,239.7
Total Assets	2,362.8	2,899.9
Current Liabilities
Current portion of long-term debt	163.6	299.9
Accounts payable	99.2	99.1
Reserves for environmental remediation costs	40.5	39.8
Contract liabilities	342.2	407.2
Other current liabilities	163.4	609.7
Total Current Liabilities	808.9	1,455.7
Noncurrent Liabilities
Long-term debt	303.6	324.4
Reserves for environmental remediation costs	262.8	260.8
Pension benefits	371.8	405.2
Operating lease liabilities	35.6	35.7
Other noncurrent liabilities	179.8	184.6
Total Noncurrent Liabilities	1,153.6	1,210.7
Total Liabilities	1,962.5	2,666.4
Commitments and contingencies
Stockholders’ Equity
Preferred stock, par value of $1.00; 15.0 million shares authorized; none issued or outstanding	0.0	0.0
Common stock, par value of $0.10; 150.0 million shares authorized; 80.1 million shares issued and outstanding as of September 30, 2021; 76.8 million shares issued and outstanding as of December 31, 2020	8.0	7.7
Other capital	596.0	583.0
Treasury stock at cost, 2.1 million shares as of September 30, 2021 and December 31, 2020	(64.4)	(64.4)
Retained earnings (accumulated deficit)	53.8	(65.2)
Accumulated other comprehensive loss, net of income taxes	(193.1)	(227.6)
Total Stockholders’ Equity	400.3	233.5
Total Liabilities and Stockholders’ Equity	$ 2,362.8	$ 2,899.9