Statement of Consolidated Cash Flows (Unaudited) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net income		$ 40.7	$ 52.3
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property, plant and equipment		18.4	16.9
Amortization of definite-lived intangible assets		0.7	0.8
Amortization of debt discount and debt issuance costs		0.6	0.5
Deferred income taxes		19.9	31.3
Non-cash equity compensation		6.6	5.7
Lower of cost or market inventory write-down		0.0	4.9
Gain on sale of available for sale securities		(1.3)	0.0
Non-cash unrealized gain on derivative instruments		(3.2)	(14.9)
Goodwill impairment		18.4	0.0
Loss on extinguishment of debt		0.0	11.1
Loss on disposition of property, plant and equipment		0.1	0.0
Non-cash net periodic postretirement benefit cost relating to Salaried VEBA		2.2	1.7
Other non-cash changes in assets and liabilities		(1.2)	0.9
Changes in operating assets and liabilities:
Trade and other receivables		(6.7)	(20.0)
Inventories, excluding lower of cost or market write-down		1.7	(2.8)
Prepaid expenses and other current assets		(4.2)	(2.7)
Accounts payable		10.1	3.4
Accrued liabilities		(9.8)	17.4
Annual variable cash contributions to VEBAs		(20.0)	(19.5)
Long-term assets and liabilities, net		0.1	(14.8)
Net cash provided by operating activities		73.1	72.2
Cash flows from investing activities
Capital expenditures		(39.7)	(42.3)
Purchase of available for sale securities		(128.0)	(72.4)
Proceeds from disposition of available for sale securities		184.2	30.0
Net cash provided by (used in) investing activities	[1]	16.5	(84.7)
Cash flows from financing activities
Repayment of principal and redemption premium of 8.25% Senior Notes		0.0	(206.0)
Issuance of 5.875% Senior Notes		0.0	375.0
Cash paid for debt issuance costs		0.0	(6.9)
Proceeds from stock option exercises		0.0	1.0
Repayment of capital lease		(0.1)	(0.1)
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares		(4.5)	(2.8)
Repurchase of common stock		(64.4)	(8.5)
Cash dividends and dividend equivalents paid		(17.9)	(16.3)
Net cash (used in) provided by financing activities	[1]	(86.9)	135.4
Net increase in cash, cash equivalents and restricted cash during the period		2.7	122.9
Cash, cash equivalents and restricted cash at beginning of period		67.7	83.7
Cash, cash equivalents and restricted cash at end of period		$ 70.4	$ 206.6

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