Debt (Details) - USD ($) $ in Thousands	Apr. 30, 2018	Jan. 31, 2018	Jan. 31, 2017
Debt Instrument
Other Long-term Debt	$ 23,664	$ 26,761
Debt and Capital Lease Obligations	1,619,591	1,637,909
Less-current maturities (included as Revolving credit loans and current portion of long-term debt, net)	(114,417)	(132,661)
Long-term Debt and Capital Lease Obligations	1,505,174	1,505,248
Senior Notes
Debt Instrument
Unamortized debt discount and debt issuance costs	(8,300)	(8,678)
Senior Notes, net	991,700	991,322
Senior Notes \| 3.70% Senior Notes
Debt Instrument
Debt Instrument, Face Amount	500,000	500,000	$ 500,000
Senior Notes \| 4.95% Senior Notes
Debt Instrument
Debt Instrument, Face Amount	500,000	500,000	$ 500,000
Term Loan
Debt Instrument
Loans Payable	500,000	500,000
Other Committed And Uncommitted Revolving Credit Facilities
Debt Instrument
Revolving Credit Loan	$ 104,227	$ 119,826

Unamortized debt discount and debt issuance costs

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- Definition

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

+ References

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Amount of short-term debt and current maturity of long-term debt and capital lease obligations due within one year or the normal operating cycle, if longer.

+ References

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- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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- Definition

Including the current and noncurrent portions, aggregate carrying value as of the balance sheet date of loans payable (with maturities initially due after one year or beyond the operating cycle if longer).

+ References

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- Definition

Amount of long-term debt and capital lease obligation due after one year or beyond the normal operating cycle, if longer.

+ References

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- Definition

Amount of long-term debt classified as other.

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- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

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