Fair value (Fair value and carrying value of debt instruments) (Details) (USD $) In Thousands, unless otherwise specified			9 Months Ended
	Sep. 29, 2012	Dec. 31, 2011	Sep. 29, 2012 7.20% Senior Notes, Payable April 15, 2012; interest payable semiannually [Member]	Sep. 29, 2012 6.125% Notes, Payable January 15, 2016; interest payable semiannually [Member]	Sep. 29, 2012 Five-Year Senior Secured Credit Facility, Due July 8, 2016 [Member]	Sep. 29, 2012 Fair Value [Member]	Dec. 31, 2011 Fair Value [Member]	Sep. 29, 2012 Fair Value [Member] 7.20% Senior Notes, Payable April 15, 2012; interest payable semiannually [Member]	Dec. 31, 2011 Fair Value [Member] 7.20% Senior Notes, Payable April 15, 2012; interest payable semiannually [Member]	Sep. 29, 2012 Fair Value [Member] 6.125% Notes, Payable January 15, 2016; interest payable semiannually [Member]	Dec. 31, 2011 Fair Value [Member] 6.125% Notes, Payable January 15, 2016; interest payable semiannually [Member]	Sep. 29, 2012 Fair Value [Member] Five-Year Senior Secured Credit Facility, Due July 8, 2016 [Member]	Dec. 31, 2011 Fair Value [Member] Five-Year Senior Secured Credit Facility, Due July 8, 2016 [Member]	Sep. 29, 2012 Carrying Value [Member]	Dec. 31, 2011 Carrying Value [Member]	Sep. 29, 2012 Carrying Value [Member] 7.20% Senior Notes, Payable April 15, 2012; interest payable semiannually [Member]	Dec. 31, 2011 Carrying Value [Member] 7.20% Senior Notes, Payable April 15, 2012; interest payable semiannually [Member]	Sep. 29, 2012 Carrying Value [Member] 6.125% Notes, Payable January 15, 2016; interest payable semiannually [Member]	Dec. 31, 2011 Carrying Value [Member] 6.125% Notes, Payable January 15, 2016; interest payable semiannually [Member]	Sep. 29, 2012 Carrying Value [Member] Five-Year Senior Secured Credit Facility, Due July 8, 2016 [Member]	Dec. 31, 2011 Carrying Value [Member] Five-Year Senior Secured Credit Facility, Due July 8, 2016 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes payable								$ 0	$ 336,606	$ 1,006,200	$ 963,900	$ 572,850	$ 298,000			$ 0	$ 336,270	$ 900,000	$ 900,000	$ 572,850	$ 298,000
Industrial revenue bonds, capital leases and other						52,092	52,169							52,092	52,169
Total long-term debt						1,631,142	1,650,675							1,524,942	1,586,439
Less current portion	57,673	386,255				57,673	386,591							57,673	386,255
Long-term debt, less current portion						$ 1,573,469	$ 1,264,084							$ 1,467,269	$ 1,200,184
Lines of credit, maturity date			Apr. 15, 2012	Jan. 15, 2016	Jul. 08, 2016