Stockholders' Equity Dividend (Details) - USD ($) $ / shares in Units, $ in Thousands				3 Months Ended								12 Months Ended
	Mar. 31, 2016	Mar. 10, 2016	Mar. 03, 2016	Jan. 31, 2016	Oct. 31, 2015	Jul. 31, 2015	Apr. 30, 2015	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Dividends Payable [Line Items]
Dividends Payable, Date Declared				Nov. 19, 2015	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				Dec. 15, 2015	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				Jan. 04, 2016	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	$ 0.055	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.22	$ 0.20	$ 0.18
Payments of Dividends				$ 6,326	$ 6,491	$ 6,389	$ 6,383	$ 5,743	$ 5,697	$ 5,693	$ 5,778	$ 25,590	$ 22,911	$ 20,398
Subsequent Event
Dividends Payable [Line Items]
Dividends Payable, Date Declared			Mar. 03, 2016
Dividends Payable, Date of Record		Mar. 10, 2016
Dividends Payable, Date to be Paid	Mar. 31, 2016
Cash dividends declared per common share			$ 0.055