CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 710.6	$ 264.3
Short-term investments		78.7
Receivables:
Trade receivables, net	126.4	167.1
Other	22.0	18.1
Contract assets	41.6	54.6
Inventories	181.4	177.6
Prepaid expenses and other current assets	25.7	19.4
Total current assets	1,107.7	779.8
Property, plant and equipment, net	627.1	622.0
Operating lease assets	28.0	25.8
Deferred tax assets, net		11.8
Intangible assets, net	28.1	29.6
Goodwill	18.8	18.8
Other assets	38.7	38.4
Total	1,848.4	1,526.2
Current liabilities:
Accounts payable	61.0	92.0
Accrued salaries, wages and related expenses	34.9	34.4
Other accrued liabilities	54.5	44.0
Total current liabilities	150.4	170.4
Long-term portion of operating lease liabilities	27.0	25.2
Net liabilities of Salaried VEBA	32.5	32.6
Deferred tax liabilities	7.3	4.5
Long-term liabilities	75.3	67.0
Long-term debt	837.1	492.6
Total liabilities	1,129.6	792.3
Commitments and contingencies
Stockholders' equity:
Preferred stock, 5,000,000 shares authorized at both June 30, 2020 and December 31, 2019; no shares were issued and outstanding at June 30, 2020 and December 31, 2019
Common stock, par value $0.01, 90,000,000 shares authorized at both June 30, 2020 and at December 31, 2019; 22,647,455 shares issued and 15,812,169 shares outstanding at June 30, 2020; 22,550,827 shares issued and 15,868,304 shares outstanding at December 31, 2019	0.2	0.2
Additional paid in capital	1,063.3	1,062.9
Retained earnings	173.4	172.8
Treasury stock, at cost, 6,835,286 shares at June 30, 2020 and 6,682,523 shares at December 31, 2019, respectively	(475.9)	(463.4)
Accumulated other comprehensive loss	(42.2)	(38.6)
Total stockholders' equity	718.8	733.9
Total	$ 1,848.4	$ 1,526.2