Income taxes Income taxes (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Oct. 31, 2014 Rate	Oct. 31, 2013 Rate
Income tax [Abstract]
effective income tax rate from continuing operations	23.60%	(0.70%)
Foreign Earnings Repatriated	$ 0.8
Open tax year	2011
Open tax years up to the amount of research tax credit generated	January 31, 2002 through January 31, 2011
Operating loss carryforwards, expiration dates beginning	Jan. 31, 2030