Derivative Instruments - Offsetting Liabilities (Detail) - USD ($) $ in Thousands	Apr. 30, 2019	Jan. 31, 2019
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	$ 752	$ 3,135
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	752
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets, Financial Instruments	(752)
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	272
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	272
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets, Financial Instruments	(272)
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	448
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	448
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets, Financial Instruments	(448)
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	32
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0
Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheets	32
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets, Financial Instruments	(32)
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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