Stockholders' Equity (Narratives) (Details) - $ / shares	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Dividends Declared
Dividends payable, date declared	Mar. 08, 2018
Dividend paid, amount per share	$ 0.5
Dividends payable, date of record	Mar. 23, 2018
Dividends payable, date to be paid	Apr. 06, 2018
Dividends declared two [Member]
Dividends Declared
Dividends payable, date declared	Dec. 06, 2017
Dividend paid, amount per share	$ 0.5
Dividends payable, date of record	Dec. 21, 2017
Dividends payable, date to be paid	Jan. 05, 2018
Dividends declared three [Member]
Dividends Declared
Dividends payable, date declared	Jul. 05, 2017
Dividend paid, amount per share	$ 1
Dividends payable, date of record	Jul. 20, 2017
Dividends payable, date to be paid	Aug. 03, 2017
Dividends declared four [Member]
Dividends Declared
Dividends payable, date declared		Feb. 08, 2017
Dividend paid, amount per share		$ 1
Dividends payable, date of record		Feb. 23, 2017
Dividends payable, date to be paid		Mar. 09, 2017
Dividends declared five [Member]
Dividends Declared
Dividends payable, date declared		Oct. 05, 2016
Dividend paid, amount per share		$ 1
Dividends payable, date of record		Oct. 20, 2016
Dividends payable, date to be paid		Nov. 03, 2016