Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 49.8	$ 60.1
Accounts receivable, net	295.6	248.7
Inventories, net	300.8	314.0
Contract assets	35.2
Prepaid expenses and other current assets	34.5	33.9
Total current assets	715.9	656.7
Property, plant and equipment	2,815.1	2,743.9
Less accumulated depreciation	(913.0)	(877.6)
Net property, plant and equipment	1,902.1	1,866.3
Goodwill and other intangible assets	150.2	148.7
Investments in affiliated companies	51.0	47.7
Other assets	65.5	61.5
Total assets	2,884.7	2,780.9
Current liabilities:
Current portions of debt	4.4	4.3
Accounts payable	154.8	144.1
Accrued compensation and benefits	64.7	73.0
Accrued liabilities	46.9	40.7
Total current liabilities	270.8	262.1
Commitments and contingencies (see Note 12)
Long-term debt	835.6	805.6
Retirement obligations	42.8	45.4
Other non-current liabilities	173.0	172.7
Total liabilities	1,322.2	1,285.8
Stockholders' equity:
Common stock, $0.01 par value, 200.0 shares authorized, 108.3 shares and 107.8 shares issued at March 31, 2018 and December 31, 2017, respectively	1.1	1.1
Additional paid-in capital	787.7	774.3
Retained earnings	1,548.7	1,496.1
Accumulated other comprehensive loss	(7.8)	(45.0)
Total stockholders' equity including treasury stock value	2,329.7	2,226.5
Less – Treasury stock, at cost, 18.7 shares at March 31, 2018, and 18.2 shares at December 31, 2017, respectively.	(767.2)	(731.4)
Total stockholders' equity	1,562.5	1,495.1
Total liabilities and stockholders' equity	$ 2,884.7	$ 2,780.9