Derivative Instruments \| Cash Flow Hedges - Impact on AOCI (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jul. 31, 2019	Jul. 31, 2019
Cash Flow Hedges - Impact on AOCI [Line Items]
Gain (loss) recognized in other comprehensive income (loss)	$ 720	$ 145
Gain (loss) reclassified from AOCI into income	451	87
Interest Expense
Cash Flow Hedges - Impact on AOCI [Line Items]
Gain (loss) reclassified from AOCI into income	168	288
Other Nonoperating Income (Expense) [Member]
Cash Flow Hedges - Impact on AOCI [Line Items]
Gain (loss) reclassified from AOCI into income	$ 283	$ (201)

Amount, after tax, of reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e689-108580

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e637-108580

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration