Stockholders Equity Dividend (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended							9 Months Ended
	Nov. 19, 2015	Oct. 31, 2015	Jul. 31, 2015	Apr. 30, 2015	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Oct. 31, 2015	Oct. 31, 2014
Dividends Payable [Line Items]
Dividends payable, date declared		Aug. 20, 2015	May 22, 2015	Feb. 26, 2015	Nov. 20, 2014	Aug. 21, 2014	May 22, 2014	Feb. 27, 2014
Dividends payable, date of record		Sep. 10, 2015	Jun. 10, 2015	Mar. 10, 2015	Dec. 10, 2014	Sep. 10, 2014	Jun. 10, 2014	Mar. 10, 2014
Dividends payable, date to be paid		Sep. 30, 2015	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	$ 0.055	$ 0.050	$ 0.050	$ 0.050	$ 0.050	$ 0.165	$ 0.150
Payments of dividends		$ 6,491	$ 6,389	$ 6,383	$ 5,743	$ 5,697	$ 5,693	$ 5,778	$ 19,263	$ 17,168
Subsequent Event [Member]
Dividends Payable [Line Items]
Dividends payable, date declared	Nov. 19, 2015
Dividends payable, date of record	Dec. 15, 2015
Dividends payable, date to be paid	Jan. 04, 2016
Cash dividends declared per common share	$ 0.055