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.