Stock-Based Compensation - Summary of Activity For Stock Settled Non-Employee Directors Stock Unit Awards (Details) - Subject To Share Settlement [Member] - Non-employee director stock unit awards [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
	Jul. 31, 2016	Jan. 31, 2016
Number of Units
Beginning balance (in shares)	24
Stock units granted (in shares)	21
Stock units vested (in shares)	(25)
Stock units forfeited (in shares)	0
Ending balance (in shares)	20	24
Weighted Averaged Grant Date Fair Value (per unit)
Beginning balance	$ 19.70
Stock units granted	23.40
Stock units vested (in dollars per share)	24.16
Ending balance	$ 23.67	$ 19.70
Aggregate Intrinsic Value
Aggregate intrinsic value of stock units vested	$ 0
Aggregate Unrecognized Compensation
Beginning balance	186
Ending balance	$ 70	$ 186
Period Over Which Expected to be Recognized (in years)
Weighted average period over which expected to be recognized	11 months	5 months