Long-Term Debt (Details) (USD $)	9 Months Ended					3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended			3 Months Ended	9 Months Ended
	Sep. 29, 2012	Oct. 01, 2011	Apr. 03, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 29, 2012 Convertible Senior Debentures 2040 [Member]	Oct. 01, 2011 Convertible Senior Debentures 2040 [Member]	Sep. 29, 2012 Convertible Senior Debentures 2040 [Member]	Oct. 01, 2011 Convertible Senior Debentures 2040 [Member]	Dec. 31, 2011 Convertible Senior Debentures 2040 [Member]	Sep. 29, 2012 Convertible Senior Debentures 2041 [Member]	Oct. 01, 2011 Convertible Senior Debentures 2041 [Member]	Sep. 29, 2012 Convertible Senior Debentures 2041 [Member]	Oct. 01, 2011 Convertible Senior Debentures 2041 [Member]	Dec. 31, 2011 Convertible Senior Debentures 2041 [Member]	Sep. 29, 2012 Convertible Senior Debentures 2042 [Member]	Sep. 29, 2012 Convertible Senior Debentures 2042 [Member]	Dec. 31, 2011 Convertible Senior Debentures 2042 [Member]
Long-Term Debt [Abstract]
Credit facility	$ 86,000,000				$ 155,000,000
Exchangeable unsecured notes, due 2102	95,042,000				95,042,000
Convertible senior debentures						99,721,000		99,721,000		98,463,000	51,190,000		51,190,000		50,549,000	57,087,000	57,087,000
Long-term Debt	389,040,000				399,054,000
Less current portion	0				0
Long-term debt, less current portion	389,040,000				399,054,000
Debt Instrument [Line Items]
Convertible senior debentures issuance date								Nov. 09, 2010					May 11, 2011				May 31, 2012
Principal amount of convertible senior debentures						275,000,000		275,000,000		275,000,000	150,000,000		150,000,000		150,000,000	150,000,000	150,000,000	0
Common stock, shares repurchased (in shares)	13,948,687																13,948,687
Treasury stock, value, acquired, cost method																	150,000,000
Principal amount of the debentures						275,000,000		275,000,000		275,000,000	150,000,000		150,000,000		150,000,000	150,000,000	150,000,000	0
Unamortized discount						(175,887,000)		(175,887,000)		(177,131,000)	(99,217,000)		(99,217,000)		(99,843,000)	(93,178,000)	(93,178,000)
Embedded derivative						608,000		608,000		594,000	407,000		407,000		392,000	265,000	265,000
Carrying value of liability component						99,721,000		99,721,000		98,463,000	51,190,000		51,190,000		50,549,000	57,087,000	57,087,000
Equity component - net carrying value						110,094,000		110,094,000		110,094,000	62,246,000		62,246,000		62,246,000	57,874,000	57,874,000
Stated rate of interest on convertible senior debentures (in hundredths)						2.25%		2.25%			2.25%		2.25%			2.25%	2.25%
Effective rate of interest on convertible senior debentures (in hundredths)								8.00%					8.375%				7.50%
Contractual coupon interest						1,547,000	1,547,000	4,641,000	4,641,000		844,000	844,000	2,532,000	1,285,000		844,000	1,135,000
Non-cash amortization of debt discount	2,160,000	1,448,000				423,000	391,000	1,244,000	1,150,000		213,000	196,000	626,000	298,000		216,000	290,000
Non-cash amortization of deferred financing costs						22,000	22,000	66,000	66,000		12,000	12,000	36,000	18,000		13,000	18,000
Non-cash change in value of derivative liability						47,000	270,000	14,000	278,000		(19,000)	161,000	15,000	163,000		(13,000)	29,000
Total interest expense related to the debentures						2,039,000	2,230,000	5,695,000	6,135,000		1,050,000	1,213,000	3,209,000	1,764,000		1,060,000	1,472,000
Debt instrument percentage of conversion price (in hundredths)																130.00%	130.00%
Debt instrument, conversion price amount																	15.35
Debt instrument, Percentage of sale price of common stock (in hundredths)																98.00%	98.00%
Debt instrument, initial conversion shares of common stock																84.6937	84.6937
Debt instrument, principal amount of debentures																1,000	1,000
Debt instrument, initial conversion price (in dollars per share)																$ 11.81	$ 11.81
Debt instrument, percentage of initial conversion price premium (in hundredths)																13.75%	13.75%
Debt instrument, conversion price (in dollars per share)																$ 10.38	$ 10.38
Line of Credit Facility, Maximum Borrowing Capacity			528,000,000	450,000,000
Line of Credit Facility, Amendment Fee Amount	$ 390,000