Segment Information (Details) - USD ($) $ in Thousands		3 Months Ended
		Apr. 30, 2020	Apr. 30, 2019	Jan. 31, 2020
Segment Reporting Information
Net sales		$ 8,175,174	$ 8,406,424
Operating income (loss):		86,115	97,624
Stock-based compensation expense		(6,307)	(8,305)
Depreciation and amortization:		41,991	37,257
Capital expenditures:		19,540	15,279
Identifiable assets:		12,376,608		$ 13,268,609
Long-lived assets:		280,736		287,150
Goodwill & acquisition-related intangible assets, net:		1,890,364		1,934,567
Acquisition, integration and restructuring expenses		17,681	6,221
Americas
Segment Reporting Information
Net sales	[1]	3,944,760	3,789,198
Operating income (loss):	[2]	49,783	68,633
Depreciation and amortization:		$ 28,213	$ 23,649
Sales to unaffiliated customers, as percentage of total sales		89.00%	88.00%
Capital expenditures:		$ 9,385	$ 8,272
Identifiable assets:		5,494,992		6,147,771
Long-lived assets:	[1]	226,234		231,401
Goodwill & acquisition-related intangible assets, net:		$ 1,321,621		$ 1,339,375
Long-lived assets, as percentage of total assets		97.00%		96.00%
Restructuring Charges		$ 17,000
Acquisition, integration and restructuring expenses			2,900
Europe
Segment Reporting Information
Net sales		3,971,130	4,309,500
Operating income (loss):		45,884	36,420
Depreciation and amortization:		11,992	11,510
Capital expenditures:		8,880	6,127
Identifiable assets:		6,391,331		$ 6,518,761
Long-lived assets:		50,124		51,331
Goodwill & acquisition-related intangible assets, net:		517,584		541,102
Asia-Pacific
Segment Reporting Information
Net sales		259,284	307,726
Operating income (loss):		(3,245)	876
Depreciation and amortization:		1,786	2,098
Capital expenditures:		1,275	$ 880
Identifiable assets:		490,285		602,077
Long-lived assets:		4,378		4,418
Goodwill & acquisition-related intangible assets, net:		$ 51,159		$ 54,090

[1] Net sales in the United States represented 89% and 88%, respectively, of the total Americas' net sales for the three months ended April 30, 2020 and 2019. Total long-lived assets in the United States represented 97% and 96%, respectively, of the Americas' total long-lived assets at April 30, 2020 and January 31, 2020.

[2] Operating income in the Americas for the three months ended April 30, 2020 and 2019 includes acquisition, integration and restructuring expenses of $17.0 million and $2.9 million, respectively (see further discussion in Note 4 – Acquisition, Integration and Restructuring Expenses).