Lease information Property under capitalized leases (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Property, Plant and Equipment [Line Items]
Machinery and Equipment, Gross	$ 51,809	$ 50,066
Capital leases lessee vehicle equipment [Line Items]	42	63
Capital Leases, Lessee Balance Sheet, Assets by Major Class, Other Property, Plant, and Equipment, Gross	92	208
Capital Leased Assets, Gross	3,459	2,227
Capital Leases, Lessee Balance Sheet, Assets by Major Class, Property, Plant, and Equipment Other, Accumulated Depreciation	546	241
Capital Leases, Balance Sheet, Assets by Major Class, Net	2,913	1,986
Noncash or Part Noncash Acquisition, Fixed Assets Acquired	569	917	845
Other Capitalized Property Plant and Equipment [Member]
Property, Plant and Equipment [Line Items]
Machinery and Equipment, Gross	$ 3,325	$ 1,956