Fair Value Measurements - Additional Information (Details)	3 Months Ended
Apr. 30, 2018 USD ($)
Fair Value Disclosures [Abstract]
Fair value, transfers into level 1	$ 0
Fair value, transfers out of level 1	0
Fair value, transfers into level 2	0
Fair value, transfers out of level 2	0
Fair value, transfers into level 3	0
Fair value, transfers out of level 3	$ 0

No definition available.

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- Definition

Amount of transfers of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset) into level 3 of the fair value hierarchy.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19279-110258

+ Details

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- Definition

Amount of transfers of financial instrument classified as derivative asset (liability) after deduction of derivative liability (asset) out of level 3 of the fair value hierarchy.

+ References

+ Details

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- Definition

Fair value net derivative asset liability measured on recurring basis unobservable inputs reconciliation transfers into level1.

+ References

No definition available.

+ Details

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- Definition

Fair value net derivative asset liability measured on recurring basis unobservable inputs reconciliation transfers into level2.

+ References

No definition available.

+ Details

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- Definition

Fair value net derivative asset liability measured on recurring basis unobservable inputs reconciliation transfers out of level1.

+ References

No definition available.

+ Details

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- Definition

Fair value net derivative asset liability measured on recurring basis unobservable inputs reconciliation transfers out of level2.

+ References

No definition available.

+ Details

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