Segment Information (Details) - USD ($) $ in Thousands		3 Months Ended																12 Months Ended
		Jan. 31, 2020		Oct. 31, 2019		Jul. 31, 2019		Apr. 30, 2019		Jan. 31, 2019		Oct. 31, 2018		Jul. 31, 2018		Apr. 30, 2018		Jan. 31, 2020	Jan. 31, 2019		Jan. 31, 2018
Segment Reporting Information
Net sales		$ 10,380,809		$ 9,118,944		$ 9,092,244		$ 8,406,424		$ 10,464,501		$ 9,340,029		$ 8,886,101		$ 8,548,319		$ 36,998,421	$ 37,238,950		$ 33,597,841
Stock-based compensation expense																		(32,187)	(31,513)		(29,381)
Operating income (loss):		218,070	[1]	141,888	[1]	124,747	[1]	97,624	[1]	166,053	[2],[3]	146,888	[2],[4],[5]	110,365	[2],[4]	70,496	[2],[4]	582,329	493,802		410,079
Depreciation and amortization:																		153,099	158,997		150,046
Capital expenditures:																		84,822	61,414		231,937
Identifiable assets:		13,268,609								12,986,552								13,268,609	12,986,552
Long-lived assets:		287,150								274,917								287,150	274,917
Goodwill & acquisition-related intangible assets, net:		1,934,567								1,719,629								1,934,567	1,719,629
Business Combination, Acquisition Related Costs		10,000		$ 4,600		$ 5,200		$ 6,200		21,100		20,300		13,300		33,200		26,030	87,920		136,272
Allowance for Doubtful Accounts Receivable												25,000
Legal settlements and other, net												$ (7,200)		$ (5,200)		$ (3,000)		(633)	(15,406)		(41,343)
Gain on disposal of subsidiary																		1,390	6,746		0
Goodwill Impairment										47,400								0	47,434		0
Americas
Segment Reporting Information
Net sales	[6]																	16,600,023	16,041,103		14,419,221
Operating income (loss):	[7],[8]																	333,233	366,637		248,350
Depreciation and amortization:																		$ 98,151	$ 93,612		$ 84,265
U.S. Sales as Percentage of Total Americas Sales																		90.00%	90.00%		89.00%
Capital expenditures:																		$ 50,953	$ 37,141		$ 207,399
Identifiable assets:		6,147,771								5,402,316								6,147,771	5,402,316
Long-lived assets:	[6]	231,401								217,863								231,401	217,863
Goodwill & acquisition-related intangible assets, net:		$ 1,339,375								$ 1,083,699								$ 1,339,375	$ 1,083,699
Long-lived Assets, as Percentage of Total Assets		96.00%								96.00%								96.00%	96.00%
Business Combination, Acquisition Related Costs																		$ 16,100	$ 25,200		75,500
Allowance for Doubtful Accounts Receivable																			25,000
Legal settlements and other, net																		(600)	(15,400)		(42,600)
Europe
Segment Reporting Information
Net sales																		19,132,040	20,026,057		18,147,917
Operating income (loss):	[9]																	272,498	195,375		173,611
Depreciation and amortization:																		47,217	56,533		57,794
Capital expenditures:																		30,895	20,818		21,471
Identifiable assets:		$ 6,518,761								$ 6,970,822								6,518,761	6,970,822
Long-lived assets:		51,331								52,162								51,331	52,162
Goodwill & acquisition-related intangible assets, net:		541,102								575,776								541,102	575,776
Business Combination, Acquisition Related Costs																		8,400	57,700		56,200
Gain on disposal of subsidiary																		1,400	6,700
Asia Pacific [Member]
Segment Reporting Information
Net sales																		1,266,358	1,171,790		1,030,703
Operating income (loss):																		8,785	(36,697)	[10]	17,499
Depreciation and amortization:																		7,731	8,852		7,987
Capital expenditures:																		2,974	3,455		$ 3,067
Identifiable assets:		602,077								613,414								602,077	613,414
Long-lived assets:		4,418								4,892								4,418	4,892
Goodwill & acquisition-related intangible assets, net:		$ 54,090								$ 60,154								$ 54,090	60,154
Goodwill Impairment																			$ 47,400

[1] During the first, second, third and fourth quarters of fiscal 2020, the Company recorded $6.2 million, $5.2 million, $4.6 million and $10.0 million of acquisition, integration and restructuring expenses, respectively (see Note 6 – Acquisition, Integration and Restructuring Expenses for further discussion).

[2] During the first, second, third and fourth quarters of fiscal 2019, the Company recorded $33.2 million, $13.3 million, $20.3 million and $21.1 million of acquisition, integration and restructuring expenses, respectively.

[3] During the fourth quarter of fiscal 2019, the Company recorded goodwill impairment expense of $47.4 million (see Note 4 – Goodwill and Intangible Assets for further discussion).

[4] During the first, second and third quarters of fiscal 2019, the Company recorded a gain of $3.0 million, $5.2 million and $7.2 million, respectively, in legal settlements and other, net.

[5] During the third quarter of fiscal 2019, the Company included a $25 million benefit in operating income related to the collection of an accounts receivable balance previously considered uncollectible.

[6] Net sales in the U.S. represented 90%, 90% and 89% of the total Americas' net sales for the fiscal years ended January 31, 2020, 2019 and 2018, respectively. Total long-lived assets in the U.S. represented 96% of the Americas' total long-lived assets at both January 31, 2020 and 2019, respectively.

[7] Operating income in the Americas for the fiscal years ended January 31, 2020, 2019 and 2018 includes acquisition, integration and restructuring expenses of $16.1 million, $25.2 million and $75.5 million, respectively (see Note 6 – Acquisition, Integration and Restructuring Expenses for further discussion). Operating income in the Americas for the fiscal year ended January 31, 2019 includes a benefit of approximately $25 million related to the collection of an accounts receivable balance previously considered uncollectible.

[8] Operating income in the Americas for the fiscal years ended January 31, 2020, 2019 and 2018 includes a gain recorded in legal settlements and other, net, of $0.6 million, $15.4 million and $42.6 million, respectively (see Note 1 – Business and Summary of Significant Accounting Policies for further discussion).

[9] Operating income in Europe for the fiscal years ended January 31, 2020, 2019 and 2018 includes acquisition, integration and restructuring expenses of $8.4 million, $57.7 million and $56.2 million, respectively.

[10] Operating income in Asia-Pacific for the fiscal year ended January 31, 2019 includes goodwill impairment expense of $47.4 million (see Note 4 – Goodwill and Intangible Assets for further discussion).