Restatement of the Unaudited Consolidated Financial Statements (Shareholders' Equity) (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2016	Apr. 30, 2015	Jan. 31, 2016	Jan. 31, 2015
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income	$ 5,519	$ 4,861
Paid-in capital	53,832	53,275	$ 53,907
Retained earnings	230,207	244,055	229,443
Total shareholders' equity	259,863	$ 302,150	$ 264,229	$ 305,237
As Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income	5,525
Paid-in capital	54,755
Retained earnings	233,926
Total shareholders' equity	264,505
Restatement Adjustments [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income	(6)
Paid-in capital	(923)
Retained earnings	(3,719)
Total shareholders' equity	$ (4,642)