Income Taxes (Details) (USD $) In Thousands, unless otherwise specified				12 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2013 UNITED STATES	Jan. 31, 2013 CANADA
Income Tax Contingency [Line Items]
Pre-tax book income, domestic				$ 76,680
Pre-tax book income, foreign					900
Total unrecognized tax benefits that, if recognized, would affect the company's effective tax rate	2,738	2,318	2,023
Accrued interest and penalties related to unrecognized tax benefits	$ 1,605	$ 1,379	$ 1,112