Convertible Debentures and Revolving Credit Facility (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2011	Jan. 01, 2011	Dec. 31, 2011	Jan. 01, 2011
Debt Instrument [Line Items]
Amortization of debt discount			$ 11,629	$ 10,084
2.625% Senior Convertible Debentures [Member]
Debt Instrument [Line Items]
Contractual coupon interest	3,938	3,938	11,813	8,925
Amortization of debt issuance costs	362	362	1,086	845
Amortization of debt discount	2,763	2,763	8,289	6,976
Total interest expense related to the debentures	7,063	7,063	21,188	16,746
3.125% Debentures [Member]
Debt Instrument [Line Items]
Contractual coupon interest	5,388	5,388	16,163	16,163
Amortization of debt issuance costs	55	56	168	168
Amortization of embedded derivative	14	14	43	43
Amortization of debt discount	1,133	1,055	3,339	3,108
Total interest expense related to the debentures	$ 6,590	$ 6,513	$ 19,713	$ 19,482