Acquisitions of and Investments in Businesses and Technologies Changes in the net carrying value of the investment in SST (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2010
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Balance at beginning of year	$ 4,728	$ 5,010
Acquisition	0	0	5,000
Raven's share of SST earnings	156	195	10
Balance at end of year	4,409	4,728	5,010
SST [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Balance at beginning of year	4,728	5,010	0
Acquisition	0	0	5,000
Raven's share of SST earnings	156	195	10
Amortization of intangible assets	(475)	(477)	0
Balance at end of year	$ 4,409	$ 4,728	$ 5,010