Statement of Consolidated Cash Flows (Unaudited) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net income		$ 28.0	$ 25.7
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property, plant and equipment		11.2	10.1
Amortization of definite-lived intangible assets		0.7	0.4
Amortization of debt discount and debt issuance costs		0.3	0.3
Deferred income taxes		10.4	7.9
Non-cash equity compensation		2.4	2.8
Gain on disposition of available for sale securities		(0.3)	(1.1)
Non-cash asset impairment charge		0.0	0.1
Other non-cash changes in assets and liabilities		3.6	8.1
Changes in operating assets and liabilities:
Trade and other receivables		(12.8)	(23.0)
Contract assets		(3.5)	(1.9)
Inventories		(18.8)	(9.6)
Prepaid expenses and other current assets		(3.4)	(2.2)
Accounts payable		7.4	32.0
Accrued liabilities		(0.4)	(7.3)
Annual variable cash contributions to VEBAs		(2.1)	(15.7)
Long-term assets and liabilities, net		0.1	(0.5)
Net cash provided by (used in) operating activities		22.8	26.1
Cash flows from investing activities
Capital expenditures		(13.6)	(19.7)
Purchase of available for sale securities		(18.1)	0.0
Proceeds from disposition of property, plant and equipment		32.7	100.3
Net cash provided by investing activities	[1]	1.0	80.6
Cash flows from financing activities
Repayment of finance lease		(0.3)	(0.2)
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares		(5.0)	(6.9)
Repurchase of common stock		(18.5)	(5.7)
Cash dividends and dividend equivalents paid		(10.2)	(10.0)
Net cash used in financing activities	[1]	(34.0)	(22.8)
Net increase in cash, cash equivalents and restricted cash during the period		(10.2)	83.9
Cash, cash equivalents and restricted cash at beginning of period		139.6	64.3
Cash, cash equivalents and restricted cash at end of period		$ 129.4	$ 148.2

[1] See Note 12 for supplemental cash flow information.