Summary of Business and Significant Accounting Policies (Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance as of beginning of year	$ (14,330)
Amortization of prior service cost (credit)	1,328	$ 2,013	$ 1,283
Net current period other comprehensive income	2,936	5,904	(6,254)
Balance as of end of year	(11,394)	(14,330)
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance as of beginning of year	(14,330)	(20,234)
Other comprehensive income before reclassifications	1,608	3,891
Amortization of prior service cost (credit)	1,328	2,013
Net current period other comprehensive income	2,936	5,904	(6,254)
Balance as of end of year	$ (11,394)	$ (14,330)	$ (20,234)