Dividends and Treasury Stock Dividends paid (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
		Apr. 30, 2018	Apr. 30, 2017
Stockholders' Equity Note [Abstract]
Payments of Ordinary Dividends, Common Stock	[1]	$ 4,658	$ 4,691
Cash dividends paid per common share (in dollars per share)		$ 0.13	$ 0.13
Dividends Payable		$ 0	$ 0

[1] There were no declared and unpaid shareholder dividends at April 30, 2018 or 2017.