Consolidated Statements of Income and Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013	Jun. 30, 2014		Jun. 30, 2013
Income Statement [Abstract]
Net sales	$ 1,468,388		$ 800,230	$ 2,899,713		$ 1,555,437
Cost of sales	(1,157,580)		(604,980)	(2,287,501)		(1,174,941)
Gross profit	310,808		195,250	612,212		380,496
Selling, general, and administrative expenses	(122,848)		(74,225)	(239,362)		(149,510)
Other expense, net	(7,712)		(10,828)	(31,694)		(14,789)
Income from operations	180,248	[1]	110,197	341,156	[1]	216,197
Interest expense, net	(21,409)	[1]	(9,232)	(42,200)	[1]	(18,483)
Income before taxes	158,839	[1]	100,965	298,956	[1]	197,714
Income tax provision	(59,282)		(34,713)	(109,313)		(69,168)
Net income	99,557		66,252	189,643		128,546
Net income per common share:
Basic	$ 1.01		$ 0.69	$ 1.93		$ 1.33
Diluted	$ 1.01		$ 0.68	$ 1.93		$ 1.32
Dividends declared per common share	$ 0.40		$ 0.40	$ 0.80		$ 0.71
Statements of Comprehensive Income:
Net income	99,557		66,252	189,643		128,546
Foreign currency translation adjustment, net of tax of $70, $0, $30, and $0, respectively	(74)		0	(92)		0
Reclassification adjustments to cash flow hedges included in net income, net of tax of $553, $553, $1,115, and $1,105, respectively	869		870	1,729		1,739
Amortization of pension and postretirement plans actuarial loss and prior service cost, net of tax of $688, $4,221, $1,472, and $5,421, respectively	1,078		6,645	2,057		8,534
Changes in unfunded employee benefit obligation, net of tax of $0, $5,370, $0, and $5,370, respectively	0		8,455	0		8,455
Other comprehensive income	1,873		15,970	3,694		18,728
Comprehensive income	$ 101,430		$ 82,222	$ 193,337		$ 147,274

[1] On October 25, 2013, we acquired Boise. The 2014 results include Boise for the full period.