Corporate Debt (Future Annual Contractual Principal Payment Commitments) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014		Mar. 31, 2014		Sep. 30, 2013	Jul. 31, 2013
Long-term Debt, Fiscal Year Maturity [Abstract]
Year Ended March 31, 2015	$ 28,969
Year Ended March 31, 2016	0
Year Ended March 31, 2017	41,850
Year Ended March 31, 2018	139,500
Year Ended March 31, 2019	285,000
Thereafter	225,000
Total	720,319
Less aggregate unamortized discount	(8,608)
Carrying value of debt outstanding	711,711		677,160
Senior Revolving Credit Facility [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Year Ended March 31, 2015	0
Year Ended March 31, 2016	0
Year Ended March 31, 2017	0
Year Ended March 31, 2018	139,500
Year Ended March 31, 2019	0
Thereafter	0
Total	139,500
Convertible Senior Subordinated Notes [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Total	130,819		142,185
Less aggregate unamortized discount	(6,540)		(10,397)
Carrying value of debt outstanding	124,279		131,788
5.25% Senior Notes [Member] | Senior Secured Second-Priority Notes [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Year Ended March 31, 2015	0
Year Ended March 31, 2016	0
Year Ended March 31, 2017	0
Year Ended March 31, 2018	0
Year Ended March 31, 2019	225,000
Thereafter	0
Total	225,000
Carrying value of debt outstanding	225,000		225,000
Coupon rate	5.25%				5.25%	5.25%
Term Loan [Member] | Term Loan [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Year Ended March 31, 2015	0
Year Ended March 31, 2016	0
Year Ended March 31, 2017	0
Year Ended March 31, 2018	0
Year Ended March 31, 2019	0
Thereafter	225,000
Total	225,000
Less aggregate unamortized discount	(2,068)		(2,247)			(2,500)
Carrying value of debt outstanding	222,932		222,753			222,500
April 2009 Notes [Member] | Convertible Senior Subordinated Notes [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Year Ended March 31, 2015	28,969	[1]
Year Ended March 31, 2016	0	[1]
Year Ended March 31, 2017	0	[1]
Year Ended March 31, 2018	0	[1]
Year Ended March 31, 2019	0	[1]
Thereafter	0	[1]
Total	28,969	[2]	40,220	[2]
Less aggregate unamortized discount	(1,676)	[2]	(4,605)	[2]
Carrying value of debt outstanding	27,293	[2]	35,615	[2]
Conversion price per share	$ 8.19
Coupon rate	3.625%
January 2012 Notes [Member] | Convertible Senior Subordinated Notes [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Year Ended March 31, 2015	0	[1]
Year Ended March 31, 2016	0	[1]
Year Ended March 31, 2017	41,850	[1]
Year Ended March 31, 2018	0	[1]
Year Ended March 31, 2019	0	[1]
Thereafter	0	[1]
Total	41,850	[2]	41,850	[2]
Less aggregate unamortized discount	(4,864)	[2]	(5,792)	[2]
Carrying value of debt outstanding	36,986	[2]	36,058	[2]
Conversion price per share	$ 10.42
Coupon rate	4.00%
April 2013 Notes [Member] | Convertible Senior Subordinated Notes [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Year Ended March 31, 2015	0	[1]
Year Ended March 31, 2016	0	[1]
Year Ended March 31, 2017	0	[1]
Year Ended March 31, 2018	0	[1]
Year Ended March 31, 2019	60,000	[1]
Thereafter	0	[1]
Total	60,000	[3]	60,000	[3]
Less aggregate unamortized discount	0	[3]	0	[3]
Carrying value of debt outstanding	$ 60,000	[3]	$ 60,000	[3]
Conversion price per share	$ 29.78
Coupon rate	1.25%

[1] The future repayment dates of the convertible senior subordinated notes represent the next redemption date by holders for each series of notes respectively, as described below.

[2] The convertible senior subordinated notes provide, with the exception of the 1.25% Convertible Senior Subordinated Notes issued in April 2013 (the "April 2013 1.25% Notes"), at the Company's option, that the conversion of the notes may be settled in cash rather than in the Company's common shares, or a combination of cash and the Company's common shares. Accounting rules require that convertible debt instruments that may be settled in cash upon conversion (including partial cash settlement) are recorded by separately accounting for the liability and equity component (i.e., conversion feature), thereby reducing the principal amount with a debt discount that is amortized as interest expense over the expected life of the note using the effective interest method. The effective interest rate on the liability component of the 3.625% Convertible Senior Subordinated Notes issued in April 2009 (the "April 2009 3.625% Notes") is 17.26%, and the effective interest rate on the liability component of the 4.00% Convertible Senior Subordinated Notes issued in January 2012 (the "January 2012 4.00% Notes") is 9.56%.

[3] The April 2013 1.25% Notes are convertible only into the Company's common shares, and do not carry an option to be settled in cash upon conversion. Accordingly, the April 2013 1.25% Notes have been recorded at their principal amount and are not reduced by a debt discount for the equity component.