Interim Financial Information (Unaudited) (Condensed Income Statement)(Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 31, 2016	Oct. 31, 2015	Jul. 31, 2015	Apr. 30, 2015	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Operating Expenses, Restatement and Remediation Related					$ 2,300	$ 2,100	$ 5,400	$ 12,200	$ 829	$ 22,043	$ 53,791
Gain (Loss) Related to Litigation Settlement		$ 5,100			35,400	3,000	21,500	38,500	98,433	5,059	35,511
Operating expenses, value added tax assessments									(8,796)	(6,229)	0
Net sales	$ 7,483,621	6,428,540	$ 6,580,393	$ 5,887,229	7,339,491	6,761,181	6,841,809	6,728,151	26,379,783	27,670,632	26,821,904
Gross profit	354,649	314,844	325,279	291,889	372,269	334,985	351,372	335,328	1,286,661	1,393,954	1,362,346
Operating income	145,202	68,053	106,235	81,938	101,684	66,745	67,710	31,496	$ 401,428	$ 267,635	$ 227,513
Net income	$ 96,147	$ 41,900	$ 76,412	$ 51,277	$ 80,677	$ 41,700	$ 39,328	$ 13,467
Net income per share
Basic (in USD per share)	$ 2.74	$ 1.19	$ 2.09	$ 1.39	$ 2.12	$ 1.09	$ 1.03	$ 0.35	$ 7.40	$ 4.59	$ 4.73
Diluted (in USD per share)	$ 2.72	$ 1.18	$ 2.09	$ 1.38	$ 2.11	$ 1.09	$ 1.03	$ 0.35	$ 7.36	$ 4.57	$ 4.71
Reversal of valuation allowance									$ 11,300	$ 29,800
Undistributed Earnings from Foreign Subsidiaries	$ 0				$ 5,598				0	5,598
Europe
Condensed Financial Statements, Captions [Line Items]
Operating expenses, value added tax assessments							$ (6,200)
Net income per share
Reversal of valuation allowance	19,200									19,200	$ 45,300
Spain
Condensed Financial Statements, Captions [Line Items]
Operating expenses, value added tax assessments										(6,200)
Spain | Value added tax assessment
Condensed Financial Statements, Captions [Line Items]
Operating expenses, value added tax assessments									(16,400)	$ (6,200)
European Subsidiary | Value added tax assessment
Condensed Financial Statements, Captions [Line Items]
Operating expenses, value added tax assessments	$ 800		$ (9,600)						$ 7,600