Statement of Consolidated Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net income	$ 85.8	$ 25.1	$ 12.0
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property, plant and equipment	24.7	23.0	19.5
Amortization of definite-lived intangible assets	1.8	2.2	0.3
Amortization of debt discount and debt issuance costs	9.8	8.6	4.5
Deferred income taxes	52.0	17.6	13.3
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	(1.3)	(0.2)	0
Non-cash equity compensation	5.8	5.4	4.7
Net non-cash LIFO (benefit) charges	(4.9)	(7.1)	16.5
Non-cash unrealized (gains) losses on derivative instruments	(16.0)	25.9	5.5
Amortization of option premiums paid (received), net	0.3	(1.2)	1.8
Non-cash impairment charges	4.4	0	4.6
(Gain) losses on disposition of property, plant and equipment	(0.1)	0.2	0.1
Non-cash net periodic benefit (income) costs	(11.5)	(5.7)	5.1
Long-term assets and liabilities, net	1.2	0.4	(0.7)
Changes in operating assets and liabilities, net of effect of acquisition:
Trade and other receivables	(27.1)	(8.3)	(1.2)
Receivable from affiliate	0	0	(0.2)
Inventories (excluding LIFO adjustments)	24.6	(24.5)	(56.3)
Prepaid expenses and other current assets	1.4	(2.9)	(0.9)
Accounts payable	(1.3)	10.9	4.2
Accrued liabilities	10.4	(1.5)	0.4
Payable to affiliate	(6.5)	(2.7)	8.1
Long-term assets and liabilities, net	(1.1)	(2.4)	24.6
Net cash provided by operating activities	152.4	62.8	66.3
Cash flows from investing activities:
Capital expenditures	(44.1)	(32.5)	(38.9)
Purchase of available for sale securities	(85.0)	(0.3)	(4.4)
Proceeds from disposal of property, plant and equipment	0.3	0.7	4.8
Cash payment for acquisition of manufacturing facility and related assets (net of $4.9 of cash received in connection with the acquisition in 2011)	0	(83.2)	(9.0)
Change in restricted cash	6.9	(1.0)	1.1
Net cash used in investing activities	(121.9)	(116.3)	(46.4)
Cash flows from financing activities:
Proceeds from issuance of Senior Notes	225.0	0	0
Proceeds from issuance of Convertible Notes	0	0	175.0
Purchase of call option in connection with issuance of cash convertible senior notes	0	0	(31.4)
Proceeds from issuance of warrants	0	0	14.3
Repayment of capital lease	(0.1)	(0.1)	0
Repayment of promissory notes	(4.7)	(8.3)	(0.7)
Cash paid for financing costs	(6.6)	(2.1)	(8.6)
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	1.3	0.2	0
Repurchase of common stock to cover employees' tax withholdings upon vesting of non-vested shares	2.2	3.1	0
Repurchase of common stock	0	0	44.2
Cash dividend paid to stockholders	(19.6)	(18.9)	(19.0)
Net cash provided by (used in) financing activities	193.1	(32.3)	85.4
Net increase (decrease) in cash and cash equivalents during the period	223.6	(85.8)	105.3
Cash and cash equivalents at beginning of period	49.8	135.6	30.3
Cash and cash equivalents at end of period	$ 273.4	$ 49.8	$ 135.6