Dividends and Treasury Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Mar. 21, 2016	Jan. 31, 2016
Stockholders' Equity Note [Abstract]
Dividends paid	$ 4,691	$ 4,701
Cash dividends paid per common share (in dollars per share)	$ 0.13	$ 0.13000
Dividends Payable	$ 0	$ 0
Stock Repurchase Program, Authorized Amount	$ 50,000	$ 50,000		$ 40,000
Stock repurchase program, additional amount authorized			$ 10,000
Shares repurchased, Treasury Stock	0	382,065
Payments for Repurchase of Common Stock	$ 0	$ 5,702
Unpaid repurchases of common stock	0	$ 0
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 12,959