Statement of Consolidated Cash Flows (Unaudited) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net income		$ 25.7	$ 36.0
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property, plant and equipment		10.1	9.2
Amortization of definite-lived intangible assets		0.4	0.4
Amortization of debt discount and debt issuance costs		0.3	0.3
Deferred income taxes		7.9	18.1
Non-cash equity compensation		2.8	3.0
Gain on disposition of available for sale securities		(1.1)	(0.7)
Non-cash unrealized loss (gain) on derivative instruments		0.0	(15.1)
Non-cash asset impairment charge		0.1	0.0
Other non-cash changes in assets and liabilities		8.1	(0.1)
Changes in operating assets and liabilities:
Trade and other receivables		(23.0)	(19.2)
Increase (Decrease) in Contract Receivables, Net		(1.9)	0.0
Inventories		(9.6)	(1.9)
Prepaid expenses and other current assets		(2.2)	(3.3)
Accounts payable		32.0	9.4
Accrued liabilities		(7.3)	(11.4)
Annual variable cash contributions to VEBAs		(15.7)	(20.0)
Long-term assets and liabilities, net		(0.5)	(0.6)
Net cash provided by operating activities1	[1]	26.1	4.1
Cash flows from investing activities
Capital expenditures		(19.7)	(14.8)
Purchase of available for sale securities		0.0	(74.7)
Proceeds from disposal of property, plant and equipment		100.3	110.9
Net cash provided by investing activities	[2]	80.6	21.4
Cash flows from financing activities
Repayment of capital lease		(0.2)	(0.2)
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares		(6.9)	(4.4)
Repurchase of common stock		(5.7)	(32.6)
Cash dividends and dividend equivalents paid		(10.0)	(9.3)
Net cash (used in) financing activities	[2]	(22.8)	(46.5)
Net increase (decrease) in cash, cash equivalents and restricted cash during the period		83.9	(21.0)
Cash, cash equivalents and restricted cash at beginning of period		64.3	67.7
Cash, cash equivalents and restricted cash at end of period		$ 148.2	$ 46.7

[1] See Note 8 for adjustments made to arrive at our Consolidated Balance Sheet as of January 1, 2018 upon adopting ASC 606 (as defined in Note 1).

[2] See Note 12 for the supplemental disclosure on non-cash transactions.