Dividends and Treasury Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2017	Oct. 31, 2016	Mar. 21, 2016	Jan. 31, 2016
Stockholders' Equity Note [Abstract]
Dividends paid	$ 4,648	$ 4,690	$ 14,032	$ 14,078
Cash dividends paid per common share (in dollars per share)	$ 0.13	$ 0.13	$ 0.39	$ 0.39
Dividends Payable	$ 0	$ 0	$ 0	$ 0
Stock Repurchase Program, Authorized Amount	$ 50,000	$ 50,000	$ 50,000	$ 50,000		$ 40,000
Stock repurchase program, additional amount authorized					$ 10,000
Shares repurchased, Treasury Stock	348,286	0	348,286	484,252
Payments for Repurchase of Common Stock	$ 10,000	$ 0	$ 10,000	$ 7,702
Unpaid repurchases of common stock		$ 0		$ 0
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 2,959		$ 2,959