Segment Information (Details) - USD ($) $ in Thousands		3 Months Ended
		Apr. 30, 2019	Apr. 30, 2018	Jan. 31, 2019
Segment Reporting Information
Revenues		$ 8,406,424	$ 8,548,319
Operating income (loss):		97,624	70,496
Stock-based compensation expense		(8,305)	(7,587)
Depreciation and amortization:		37,257	40,481
Capital expenditures:		15,279	8,455
Identifiable assets:		12,311,749		$ 12,986,552
Long-lived assets:		271,906		274,917
Goodwill & acquisition-related intangible assets, net:		1,688,983		1,719,629
Legal settlements and other, net		(282)	(2,965)
Acquisition, integration and restructuring expenses		6,221	33,225
Americas
Segment Reporting Information
Revenues	[1]	3,789,198	3,618,206
Operating income (loss):	[2]	68,633	61,342
Depreciation and amortization:		$ 23,649	$ 23,259
Sales to unaffiliated customers, as percentage of total sales		88.00%	87.00%
Capital expenditures:		$ 8,272	$ 4,379
Identifiable assets:		5,517,978		5,402,316
Long-lived assets:	[1]	215,504		217,863
Goodwill & acquisition-related intangible assets, net:		$ 1,070,187		$ 1,083,699
Long-lived assets, as percentage of total assets		96.00%		96.00%
Legal settlements and other, net		$ (300)	(3,000)
Acquisition, integration and restructuring expenses		2,900	13,900
Europe
Segment Reporting Information
Revenues		4,309,500	4,661,702
Operating income (loss):	[3]	36,420	17,318
Depreciation and amortization:		11,510	14,991
Capital expenditures:		6,127	3,717
Identifiable assets:		6,194,424		$ 6,970,822
Long-lived assets:		51,481		52,162
Goodwill & acquisition-related intangible assets, net:		560,214		575,776
Acquisition, integration and restructuring expenses		3,000	18,000
Asia-Pacific
Segment Reporting Information
Revenues		307,726	268,411
Operating income (loss):		876	(577)
Depreciation and amortization:		2,098	2,231
Capital expenditures:		880	$ 359
Identifiable assets:		599,347		613,414
Long-lived assets:		4,921		4,892
Goodwill & acquisition-related intangible assets, net:		$ 58,582		$ 60,154

[1] Net sales in the United States represented 88% and 87%, respectively, of the total Americas' net sales for the three months ended April 30, 2019 and 2018. Total long-lived assets in the United States represented 96% of the Americas' total long-lived assets at both April 30, 2019 and January 31, 2019.

[2] Operating income in the Americas for the three months ended April 30, 2019 and 2018 includes acquisition, integration and restructuring expenses of $2.9 million and $13.9 million, respectively (see further discussion in Note 3 – Acquisition, Integration and Restructuring Expenses). Operating income in the Americas includes a gain related to legal settlements and other, net, of $0.3 million and $3.0 million for the three months ended April 30, 2019 and 2018 (see further discussion in Note 1 - Business and Summary of Significant Accounting Policies).

[3] Operating income in Europe for the three months ended April 30, 2019 and 2018 includes acquisition, integration and restructuring expenses of $3.0 million and $18.0 million, respectively.