Derivative Instruments - Offsetting Liabilities (Detail) - USD ($) $ in Thousands	Oct. 31, 2018	Jan. 31, 2018
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	$ 540	$ 32,912
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	540
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets, Financial Instruments	(540)
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets, Cash Collateral Pledged	0
Net Liabilities Exposed	0
Counterparty A
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	91
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	91
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets, Financial Instruments	(91)
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets, Cash Collateral Pledged	0
Net Liabilities Exposed	0
Counterparty B
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	337
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	337
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets, Financial Instruments	(337)
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets, Cash Collateral Pledged	0
Net Liabilities Exposed	0
Counterparty C
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	112
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	112
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets, Financial Instruments	(112)
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets, Cash Collateral Pledged	0
Net Liabilities Exposed	$ 0

Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities.

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