Summary of Business and Significant Accounting Policies (Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of beginning of year	$ (20,234)
Amortization of prior service cost (credit)	2,013	$ 1,283	$ 1,548
Net current period other comprehensive (loss) income	5,904	(6,254)	2,006
Balance as of end of year	(14,330)	(20,234)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of beginning of year	(20,234)	(13,980)
Other comprehensive income (loss) before reclassifications	3,891	(7,537)
Amortization of prior service cost (credit)	2,013	1,283
Net current period other comprehensive (loss) income	5,904	(6,254)	2,006
Balance as of end of year	$ (14,330)	$ (20,234)	$ (13,980)