Dividends and Treasury Stock Dividends paid (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
		Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Stockholders' Equity Note [Abstract]
Payments of Ordinary Dividends, Common Stock	[1]	$ 4,674	$ 4,648	$ 14,000	$ 14,032
Cash dividends paid per common share (in dollars per share)	[1]	$ 0.130	$ 0.130	$ 0.390	$ 0.390
Dividends Payable		$ 0	$ 0	$ 0	$ 0

[1] There were no declared and unpaid shareholder dividends at October 31, 2018 or 2017.