Stockholders Equity Dividend (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended						6 Months Ended
	Aug. 20, 2015	Jul. 31, 2015	Apr. 30, 2015	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jul. 31, 2015	Jul. 31, 2014
Dividends Payable [Line Items]
Dividends payable, date declared		May 22, 2015	Feb. 26, 2015	Nov. 20, 2014	Aug. 21, 2014	May 22, 2014	Feb. 27, 2014
Dividends payable, date of record		Jun. 10, 2015	Mar. 10, 2015	Dec. 10, 2014	Sep. 10, 2014	Jun. 10, 2014	Mar. 10, 2014
Dividends payable, date to be paid		Jun. 30, 2015	Mar. 31, 2015	Jan. 02, 2015	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014
Cash dividends declared per common share		$ 0.055	$ 0.055	$ 0.050	$ 0.050	$ 0.050	$ 0.050	$ 0.110	$ 0.100
Payments of dividends		$ 6,389	$ 6,383	$ 5,743	$ 5,697	$ 5,693	$ 5,778	$ 12,772	$ 11,471
Subsequent Event [Member]
Dividends Payable [Line Items]
Dividends payable, date declared	Aug. 20, 2015
Dividends payable, date of record	Sep. 10, 2015
Dividends payable, date to be paid	Sep. 30, 2015
Cash dividends declared per common share	$ 0.055