Non-controlling interests (Details) (USD $)	3 Months Ended
	Mar. 30, 2014		Mar. 31, 2013
Balance	$ 874,408,000	[1]
Net income	16,279,000		19,604,000
Other Comprehensive Income	2,800,000
Dividends declared	(1,700,000)
Dividends to non-controlling interest	(296,000)		(486,000)
Employee benefit transactions	1,800,000
Income tax benefit arising from employee stock option plans	1,100,000
Purchase of common stock for treasury	0
Stock based compensation	300,000
Balance	894,686,000	[2]
Common Stock [Member]
Balance	4,700,000
Net income	0
Other Comprehensive Income	0
Dividends declared	0
Dividends to non-controlling interest	0
Employee benefit transactions	100,000
Income tax benefit arising from employee stock option plans	0
Purchase of common stock for treasury	0
Stock based compensation	0
Balance	4,800,000
Additional Paid-in Capital [Member]
Balance	361,500,000
Net income	0
Other Comprehensive Income	0
Dividends declared	0
Dividends to non-controlling interest	0
Employee benefit transactions	1,700,000
Income tax benefit arising from employee stock option plans	1,100,000
Purchase of common stock for treasury	0
Stock based compensation	300,000
Balance	364,600,000
Retained Earnings [Member]
Balance	1,106,300,000
Net income	15,600,000
Other Comprehensive Income	0
Dividends declared	(1,700,000)
Dividends to non-controlling interest	0
Employee benefit transactions	0
Income tax benefit arising from employee stock option plans	0
Purchase of common stock for treasury	0
Stock based compensation	0
Balance	1,120,200,000
Accumulated Other Comprehensive Income (Loss) [Member]
Balance	(31,300,000)
Net income	0
Other Comprehensive Income	3,000,000
Dividends declared	0
Dividends to non-controlling interest	0
Employee benefit transactions	0
Income tax benefit arising from employee stock option plans	0
Purchase of common stock for treasury	0
Stock based compensation	0
Balance	(28,300,000)
Treasury Stock [Member]
Balance	(593,700,000)
Net income	0
Other Comprehensive Income	0
Dividends declared	0
Dividends to non-controlling interest	0
Employee benefit transactions	0
Income tax benefit arising from employee stock option plans	0
Purchase of common stock for treasury	0
Stock based compensation	0
Balance	(593,700,000)
Noncontrolling Interest [Member]
Balance	26,900,000
Net income	600,000
Other Comprehensive Income	(200,000)
Dividends declared	0
Dividends to non-controlling interest	(300,000)
Employee benefit transactions	0
Income tax benefit arising from employee stock option plans	0
Purchase of common stock for treasury	0
Stock based compensation	0
Balance	$ 27,000,000

[1] Condensed from audited financial statements

[2] Unaudited