Change in Accounting Principle: Inventories (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended			9 Months Ended				3 Months Ended	9 Months Ended			3 Months Ended	9 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2013 Change in Accounting Method for Inventory Valuation Effect of Change in Accounting Principle	Sep. 30, 2013 Change in Accounting Method for Inventory Valuation Effect of Change in Accounting Principle	Dec. 31, 2013 Change in Accounting Method for Inventory Valuation Effect of Change in Accounting Principle	Dec. 31, 2012 Change in Accounting Method for Inventory Valuation Effect of Change in Accounting Principle	Sep. 30, 2014 Pro Forma Effect Had Inventory Change Not Been Made Change in Accounting Method for Inventory Valuation	Sep. 30, 2014 Pro Forma Effect Had Inventory Change Not Been Made Change in Accounting Method for Inventory Valuation	Sep. 30, 2013 As Previously Reported (under LIFO)		Sep. 30, 2013 As Previously Reported (under LIFO)		Dec. 31, 2013 As Previously Reported (under LIFO)
Consolidated Statements of Income and Comprehensive Income
Cost of sales	$ (1,198,607)		$ (617,841)	$ (3,486,108)		$ (1,792,782)		$ 822	$ 6,503					$ (618,663)	[1]	$ (1,799,285)	[1]
Gross profit	320,333		227,599	932,545		608,095		822	6,503					226,777	[1]	601,592	[1]
Income from operations	188,378	[2]	142,782	529,534	[2]	358,979		822	6,503					141,960	[1]	352,476	[1]
Income before taxes	165,267	[2]	130,932	464,223	[2]	328,646		822	6,503					130,110	[1]	322,143	[1]
Provision for income taxes	(60,822)		(46,250)	(170,135)		(115,418)		(320)	(2,533)					(45,930)	[1]	(112,885)	[1]
Net income	104,445		84,682	294,088		213,228		502	3,970			1,700	1,500	84,180	[1]	209,258	[1]
Comprehensive income	104,831		93,902	298,168		241,176		502	3,970					93,400	[1]	237,206	[1]
Net income per common share:
Basic (in dollars per share)	$ 1.06		$ 0.88	$ 2.99		$ 2.21		$ 0.01	$ 0.04					$ 0.87	[1]	$ 2.17	[1]
Diluted (in dollars per share)	$ 1.06		$ 0.87	$ 2.99		$ 2.19		$ 0.01	$ 0.04					$ 0.86	[1]	$ 2.15	[1]
Consolidated Balance Sheet
Inventories	616,962			616,962			594,291			71,768		(69,300)	(69,300)					522,523
Deferred income tax assets	32,280			32,280			47,616			(27,963)								75,579
Retained earnings	1,184,155			1,184,155			1,019,101			43,805	38,800							975,296
Consolidated Statement of Cash Flows
Net income	104,445		84,682	294,088		213,228		502	3,970			1,700	1,500	84,180	[1]	209,258	[1]
Deferred income tax provision				17,427		6,137			2,533							3,604
Inventories				$ (22,520)		$ (4,628)			$ (6,503)							$ 1,875

[1] Certain amounts in prior periods' consolidated financial statements have been reclassified to conform with the current period presentation.

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