Financing Arrangements-Interest (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 29, 2015	Mar. 30, 2014
1.5% Sr. Convertible Notes due 2017 [Member]
Interest Cost Recognized For Convertible Notes
Contractual interest coupon	$ 3,738	$ 3,750
Amortization of bond issuance costs	665	667
Amortization of bond discount	10,873	10,192
Total interest cost recognized	15,276	14,609
0.5% Sr. Convertible Notes due 2020 [Member]
Interest Cost Recognized For Convertible Notes
Contractual interest coupon	1,875	1,875
Amortization of bond issuance costs	627	659
Amortization of bond discount	11,254	10,771
Total interest cost recognized	$ 13,756	$ 13,305

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Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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Amount of noncash expense included in interest expense to issue debt and obtain financing associated with the related debt instruments. Alternate captions include noncash interest expense.

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Amount of the cost of borrowed funds accounted for as interest expense.

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