Interim Financial Information (Unaudited) (Condensed Income Statement) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended																12 Months Ended
		Jan. 31, 2019		Oct. 31, 2018		Jul. 31, 2018		Apr. 30, 2018		Jan. 31, 2018		Oct. 31, 2017		Jul. 31, 2017		Apr. 30, 2017		Jan. 31, 2019		Jan. 31, 2018	Jan. 31, 2017
Condensed Financial Statements, Captions
Revenues		$ 10,464,501		$ 9,340,029		$ 8,886,101		$ 8,548,319		$ 10,033,397		$ 8,448,471		$ 8,092,353		$ 7,023,620		$ 37,238,950		$ 33,597,841	$ 24,193,697
Gross profit		649,148		556,604		527,030		523,117		616,861		526,081		515,591		457,088		2,255,899		2,115,621	1,301,927
Operating income		166,053	[1],[2]	146,888	[1],[3],[4]	110,365	[1],[3]	70,496	[1],[3]	151,903	[5]	79,567	[5]	103,531	[5],[6]	75,078	[5],[6]	493,802		410,079	291,902
Net income		116,799	[7]	114,216	[7]	75,866		33,699		1,260	[8]	37,268		47,459		30,654		340,580		116,641	195,095
Gain (Loss) Related to Litigation Settlement				7,200		5,200		3,000						28,700		12,700		15,406		41,343	4,142
Acquisition, integration and restructuring expenses		$ 21,100		$ 20,300		$ 13,300		$ 33,200		34,300		$ 29,700		$ 30,100		$ 42,100		$ 87,920		136,272	$ 28,966
USTaxActImpactOnUSFederalTaxRate										$ 95,400										$ 95,400
Earnings per share:
Basic		$ 3.13		$ 2.98		$ 1.97		$ 0.88		$ 0.03		$ 0.98		$ 1.24		$ 0.82		$ 8.94		$ 3.07	$ 5.54
Diluted		$ 3.11		$ 2.96		$ 1.97		$ 0.87		$ 0.03		$ 0.97		$ 1.24		$ 0.82		$ 8.89		$ 3.05	$ 5.51
Reversal of valuation allowance																		$ 37,800		$ 33,900
US Tax Act Impact - Transition Tax		$ 25,200		$ 24,000														(49,200)		101,100
Allowance for Doubtful Accounts Receivable, Recoveries				$ 25,000
Goodwill Impairment		47,434																47,434		0	$ 0
Asia Pacific [Member]
Condensed Financial Statements, Captions
Revenues																		1,171,790		1,030,703	0
Operating income																		(36,697)	[9]	17,499	0
Earnings per share:
Goodwill Impairment		$ 47,434																47,434
Europe
Condensed Financial Statements, Captions
Revenues																		20,026,057		18,147,917	14,668,184
Operating income	[10]																	195,375		173,611	161,603
Acquisition, integration and restructuring expenses																		57,700		$ 56,200	$ 11,000
Earnings per share:
Goodwill Impairment																		$ 0

[1] 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 (see Note 6 – Acquisition, Integration and Restructuring Expenses for further discussion).

[2] 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).

[3] 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 (see Note 1 - Business and Summary of Significant Accounting Policies for further discussion).

[4] 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.

[5] During the first, second, third and fourth quarters of fiscal 2018, the Company recorded $42.1 million, $30.1 million, $29.7 million and $34.3 million of acquisition, integration and restructuring expenses, respectively.

[6] During the first and second quarters of fiscal 2018, the Company recorded a gain of $12.7 million and $28.7 million, respectively, in legal settlements and other, net.

[7] The Company decreased its estimate of the one-time transition tax related to the enactment of U.S. Tax Reform by $24.0 million and $25.2 million, respectively, in the third and fourth quarters of fiscal 2019 (see Note 9 – Income Taxes for further discussion).

[8] The Company recorded income tax expenses of $95.4 million in the fourth quarter of fiscal 2018 related to the impact of the enactment of U.S. Tax Reform.

[9] 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).

[10] Operating income in Europe for the fiscal years ended January 31, 2019, 2018 and 2017 includes acquisition, integration and restructuring expenses of $57.7 million, $56.2 million and $11.0 million, respectively.