Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash Flows from Operating Activities:
Net income (loss)	$ 13.6	$ (6.1)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Loss on divestiture of business	14.7	0.0
Depreciation and amortization expense	56.8	50.2
Deferred income tax expense	3.6	(1.1)
Settlement loss and expense for pension plan	0.0	13.1
Gain on curtailment and payments in excess of expense for postretirement plan benefits	(1.2)	(5.5)
Share-based compensation expense	3.4	4.2
Loss from equity method investment	0.0	1.4
(Gain) loss on extinguishment of debt	(23.9)	9.4
Changes in working capital pertaining to operating activities (net of the effects of divestiture):
Receivables	16.2	21.5
Inventories	15.5	36.0
Accounts payable	(5.5)	(25.4)
Accrued liabilities	7.0	(18.9)
Deferred revenue	18.2	0.0
Interest payable	(2.1)	1.9
Income taxes	1.9	(0.9)
Other	3.3	(3.2)
Net cash provided by operating activities	121.5	76.6
Cash Flows from Investing Activities:
Capital expenditures	(30.2)	(22.5)
Decrease in restricted cash	15.9	0.0
Divestiture of coal business	(12.1)	0.0
Other investing activities	2.1	0.0
Net cash used in investing activities	(24.3)	(22.5)
Cash Flows from Financing Activities:
Proceeds from issuance of long-term debt	0.0	210.8
Repayment of long-term debt	(47.0)	(149.5)
Debt issuance costs	0.0	(4.8)
Proceeds from revolving credit facility	20.0	0.0
Repayment of revolving credit facility	(60.4)	0.0
Cash distribution to noncontrolling interests	(24.7)	(18.7)
Shares repurchased	0.0	(20.0)
Proceeds from exercise of stock options, net of shares withheld for taxes	(0.5)	(0.4)
Dividends paid	0.0	(8.8)
Net cash (used in) provided by financing activities	(112.6)	8.6
Net (decrease) increase in cash and cash equivalents	(15.4)	62.7
Cash and cash equivalents at beginning of period	123.4	139.0
Cash and cash equivalents at end of period	108.0	201.7
Supplemental Disclosure of Cash Flow Information
Interest paid	30.8	25.0
Income taxes paid, net of refunds of $4.0 million in 2016 and no refunds in 2015	$ (2.2)	$ 2.2