Investments in Marketable Securities - Investment Income (Details) - USD ($)	3 Months Ended	6 Months Ended
Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Interest income	$ 322,000	$ 14,000	$ 322,000	$ 26,000
Total investment income	322,000	14,000	322,000	26,000
Realized gains or realized losses	$ 0	$ 0	$ 0	$ 0

The aggregate amount of income from investments (for example, dividends) not considered a component of the entity's core operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.7)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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