Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Foreign Corporate Tax Rate [Line Items]
Foreign Corporate Tax Rate After Enactment of Finance Act of 2011, Effective April 1, 2012	25.00%		25.00%
Foreign Corporate Tax Rate After Enactment of Finance Act of 2012, Effective April 1, 2012	24.00%		24.00%
Foreign Corporate Tax Rate After Enactment of Finance Act of 2012, Effective April 1, 2013	23.00%		23.00%
Foreign Corporate Tax Rate After Enactment of Finance Bill 2013, Effective April 1, 2014	21.00%		21.00%
Foreign Corporate Tax Rate After Enactment of Finance Bill 2013, Effective April 1, 2015	20.00%		20.00%
Tax Benefit Resulting from Foreign Tax Rate Change	$ 19,164	$ 18,075
Reduction in effective tax rate due to UK tax rate changes	17.90%	18.50%	10.50%	22.70%