Consolidated Statements of Income and Comprehensive Income (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Income Statement [Abstract]
Net sales	$ 5,852.6		$ 3,665.3		$ 2,843.9
Cost of sales	(4,623.1)		(2,797.8)		(2,209.2)
Gross profit	1,229.5		867.5		634.7
Selling, general, and administrative expenses	(469.5)		(326.6)		(280.8)
Alternative energy tax credits	0		0		95.5
Other expense, net	(57.3)		(59.0)		(11.8)
Income from operations	702.7		481.9	[1]	437.6
Interest expense, net	(88.4)	[2]	(58.3)	[1],[3]	(62.9)	[4]
Income before taxes	614.3		423.6	[1]	374.7
(Provision) benefit for income taxes	(221.7)		17.7		(214.5)
Net income	392.6		441.3		160.2
Net income per common share
Basic	$ 3.99		$ 4.57		$ 1.66
Diluted	$ 3.99		$ 4.52		$ 1.64
Dividends declared per common share	$ 1.60		$ 1.51		$ 1.00
Statement of Comprehensive Income:
Net income	392.6		441.3		160.2
Foreign currency translation adjustment	(2.6)		(0.1)		0
Fair value adjustments to cash flow hedges, net of tax of $6.5 million for 2012	0		0		(10.2)
Reclassification adjustments to cash flow hedges included in net income, net of tax of $2.2 million, $2.2 million, and $1.2 million for 2014, 2013, and 2012, respectively	3.5		3.5		1.8
Amortization of pension and postretirement plans actuarial loss and prior service cost, net of tax of $2.8 million, $8.5 million, and $4.3 million for 2014, 2013, and 2012, respectively	4.2		13.4		6.7
Changes in unfunded employee benefit obligations, net of tax of $59.2 million, $20.4 million, and $9.3 million for 2014, 2013, and 2012, respectively	(94.0)		32.2		(14.5)
Other comprehensive income (loss)	(88.9)		49.0		(16.2)
Comprehensive income	$ 303.7		$ 490.3		$ 144.0

[1] On October 25, 2013, we acquired Boise Inc. (Boise). Our financial results include Boise subsequent to acquisition.

[2] Includes $1.5 million of expense related to the write-off of deferred financing costs in connection with the debt refinancing discussed in Note 10, Debt.

[3] Includes $10.5 million of expenses for financing the acquisition and $1.1 million of expense for the write-off of deferred financing costs.

[4] Includes $24.8 million of debt refinancing charges, including a $21.3 million redemption premium, a $3.4 million charge to settle the treasury lock prior to its maturity, and $0.1 million of other items.