Discontinued operations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Discontinued operations
Net proceeds from sale of discontinued operations			$ 0	$ 16,378
Disposal date HVAC subsidiary			Jun. 26, 2013
Net sales	0	874	176	13,049
(Loss) gain on disposal of discontinued operations	295	(12)	283	9,750
(Loss) income from discontinued operations	(5)	(551)	(183)	1,627
(Loss) income from discontinued operations before income taxes	290	(563)	100	11,377
Income tax expense	25	(789)	317	1,867
(Loss) income from discontinued operations, net of tax	$ 265	$ 226	$ (217)	$ 9,510