Financing Arrangments-Interest (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 30, 2014	Mar. 31, 2013
1% Sr. Convertible Notes due 2013 [Member]
Interest Cost Recognized For Convertible Notes
Contractual interest coupon		$ 2,319
Amortization of bond issuance costs		696
Amortization of bond discount		14,058
Total interest cost recognized		17,073
1.5% Sr. Convertible Notes due 2017 [Member]
Interest Cost Recognized For Convertible Notes
Contractual interest coupon	3,750	3,750
Amortization of bond issuance costs	667	667
Amortization of bond discount	10,192	9,519
Total interest cost recognized	14,609	13,936
0.5% Sr. Convertible Notes due 2020 [Member]
Interest Cost Recognized For Convertible Notes
Contractual interest coupon	1,875
Amortization of bond issuance costs	659
Amortization of bond discount	10,771
Total interest cost recognized	$ 13,305