Equity (Earnings Per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended						3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 25, 2011	Jun. 30, 2012	Jun. 25, 2011	Jun. 30, 2012 2.25% Senior convertible debentures	Mar. 31, 2012 2.25% Senior convertible debentures	Dec. 31, 2011 2.25% Senior convertible debentures	Mar. 26, 2011 2.25% Senior convertible debentures	Jun. 30, 2012 Stock options	Jun. 25, 2011 Stock options	Jun. 30, 2012 Stock options	Jun. 25, 2011 Stock options
Antidilutive securities excluded from computation of earnings per share amount
Antidilutive securities excluded from computation of earnings per share amount (in shares)									4,672,900	4,005,165	4,534,065	4,028,815
Numerator:
Income from continuing operations for purposes of calculating earnings per share	$ 30,426	$ 34,050	$ 56,788	$ 69,330
Income (loss) from discontinued operations	$ 42	$ (1,732)	$ 119	$ (5,677)
Denominator:
Weighted average shares outstanding-Basic (in shares)	48,029,744	50,991,731	48,142,347	52,464,839
Effect of dilutive securities:
2.25% senior convertible debentures (in shares)	0	0	0	0
Stock options and contingently issued restricted stock (in shares)	383,056	689,006	439,844	687,166
Weighted average shares outstanding-Diluted (in shares)	48,412,800	51,680,737	48,582,191	53,152,005							5,447	718,089
Basic earnings per share from continuing operations attributable to common shareowners (in dollars per share)	$ 0.63	$ 0.67	$ 1.18	$ 1.32
Basic earnings (loss) per share from discontinued operations attributable to common shareowners (in dollars per share)	$ 0.00	$ (0.03)	$ 0.00	$ (0.11)
Diluted earnings per share from continuing operations attributable to common shareowners (in dollars per share)	$ 0.63	$ 0.66	$ 1.17	$ 1.30
Diluted earnings (loss) per share from discontinued operations attributable to common shareowners (in dollars per share)	$ 0.00	$ (0.03)	$ 0.00	$ (0.11)
Interest rate on debt (as a percent)					2.25%	2.25%	2.25%	2.25%