CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (Unaudited) - $ / shares	Jul. 31, 2018	Jan. 31, 2018	Jul. 31, 2017
Statement of Financial Position [Abstract]
Preferred Stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Preferred Stock, shares authorized	2,000,000	2,000,000	2,000,000.0
Preferred Stock, shares issued	0	0	0
Preferred Stock, shares outstanding	0	0	0
Common Stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Common Stock, shares authorized	240,000,000	240,000,000	240,000,000
Common Stock, shares issued	122,400,000	124,500,000	124,500,000
Common Stock, shares outstanding	122,400,000	124,500,000	124,500,000

Face amount or stated value per share of common stock.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
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Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

+ References

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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