Dividends and Treasury Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2016	Jul. 31, 2015	Mar. 21, 2016
Stockholders' Equity Note [Abstract]
Dividends paid	$ 4,687	$ 4,894	$ 9,388	$ 9,834
Cash dividends paid per common share (in dollars per share)	$ 0.13	$ 0.13	$ 0.26000	$ 0.26000
Stock Repurchase Program, Authorized Amount	$ 50,000	$ 40,000	$ 50,000	$ 40,000
Stock repurchase program, additional amount authorized					$ 10,000
Shares repurchased, Treasury Stock	102,187	400,599	484,252	549,958
Payments for Repurchase of Common Stock	$ 2,000	$ 7,781	$ 7,702	$ 10,825
Unpaid repurchases of common stock	0	$ 27	0	$ 27
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 12,959		$ 12,959