Segment Information (Details) - USD ($) $ in Thousands		3 Months Ended					12 Months Ended
		Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2018
Segment Reporting Information
Net sales:		$ 8,548,319	$ 10,033,397	$ 8,448,471	$ 8,092,353	$ 7,023,620	$ 33,597,841
Operating income:		70,496				75,078
Stock-based compensation expense		(7,587)				(4,918)
Depreciation and amortization:		40,481				31,683
Capital expenditures:		8,455				30,446
Identifiable assets:		11,419,784	12,920,359				12,920,359
Long-lived assets:		270,738	279,091				279,091
Goodwill & acquisition-related intangible assets, net:		1,873,691	1,914,500				1,914,500
LCD settlements and other, net		(2,965)				(12,688)
Acquisition, integration and restructuring expenses		33,225				42,066
Americas
Segment Reporting Information
Net sales:		3,618,206				3,135,322
Operating income:	[1]	61,342				50,900
Depreciation and amortization:		$ 23,259				$ 16,692
Sales to unaffiliated customers, as percentage of total sales	[2]	87.00%				88.00%
Capital expenditures:		$ 4,379				$ 20,872
Identifiable assets:		5,020,562	5,014,409				5,014,409
Long-lived assets:		210,307	214,922				214,922
Goodwill & acquisition-related intangible assets, net:		$ 1,120,752	$ 1,139,273				$ 1,139,273
Long-lived assets, as percentage of total assets		97.00%	97.00%				97.00%
LCD settlements and other, net		$ (3,000)				(12,700)
Acquisition, integration and restructuring expenses		13,900				30,200
Europe
Segment Reporting Information
Net sales:		4,661,702				3,707,265
Operating income:	[3]	17,318				24,799
Depreciation and amortization:		14,991				13,533
Capital expenditures:		3,717				9,394
Identifiable assets:		5,847,476	$ 7,336,974				$ 7,336,974
Long-lived assets:		55,153	57,781				57,781
Goodwill & acquisition-related intangible assets, net:		633,261	645,134				645,134
Acquisition, integration and restructuring expenses		18,000				11,600
Asia-Pacific
Segment Reporting Information
Net sales:		268,411				181,033
Operating income:		(577)				4,297
Depreciation and amortization:		2,231				1,458
Capital expenditures:		359				$ 180
Identifiable assets:		551,746	568,976				568,976
Long-lived assets:		5,278	6,388				6,388
Goodwill & acquisition-related intangible assets, net:		$ 119,678	$ 130,093				$ 130,093

[1] Operating income in the Americas for the three months ended April 30, 2018 includes acquisition, integration and restructuring expenses of $13.9 million (see further discussion in Note 4 – Acquisitions) and a gain related to LCD settlements and other, net, of $3.0 million (see further discussion in Note 1 - Business and Summary of Significant Accounting Policies). Operating income in the Americas for the three months ended April 30, 2017 includes acquisition, integration and restructuring expenses of $30.2 million and a gain related to LCD settlements and other, net, of $12.7 million

[2] Net sales in the United States represented 87% and 88%, respectively, of the total Americas' net sales for the three months ended April 30, 2018 and 2017. Total long-lived assets in the United States represented 97% of the Americas' total long-lived assets at both April 30, 2018 and January 31, 2018.

[3] Operating income in Europe for the three months ended April 30, 2018 and 2017, includes acquisition, integration and restructuring expenses of $18.0 million and $11.6 million, respectively.