Investments in Marketable Securities - Investment Income (Details) - USD ($)	3 Months Ended		9 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2017	Oct. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Interest income	$ 418,000	$ 8,000	$ 740,000	$ 34,000
Realized gains	1,000	0	1,000	0
Total investment income	419,000	8,000	741,000	34,000
Realized gains or realized losses	$ 0	$ 0	$ 0	$ 0