Noncontrolling interests (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 29, 2013	Sep. 30, 2012	Sep. 29, 2013	Sep. 30, 2012
Balance			$ 813,719,000
Consolidated net income	22,550,000	19,183,000	59,893,000	58,030,000
Other Comprehensive Income			(8,900,000)
Dividends declared			(5,200,000)
Dividends paid to non-controlling interest			(763,000)	(3,394,000)
Employee benefit transactions			11,500,000
Income tax benefit arising from employee stock option			2,600,000
Purchase of common stock			(44,000,000)
Stock based compensation			3,500,000
Balance	832,274,000		832,274,000
Common Stock [Member]
Balance			4,700,000
Consolidated net income			0
Other Comprehensive Income			0
Dividends declared			0
Dividends paid to non-controlling interest			0
Employee benefit transactions			100,000
Income tax benefit arising from employee stock option			0
Purchase of common stock			0
Stock based compensation			0
Balance	4,800,000		4,800,000
Additional Paid-in Capital [Member]
Balance			345,900,000
Consolidated net income			0
Other Comprehensive Income			0
Dividends declared			0
Dividends paid to non-controlling interest			0
Employee benefit transactions			11,400,000
Income tax benefit arising from employee stock option			2,600,000
Purchase of common stock			0
Stock based compensation			3,500,000
Balance	363,400,000		363,400,000
Retained Earnings [Member]
Balance			1,032,900,000
Consolidated net income			57,700,000
Other Comprehensive Income			0
Dividends declared			(5,200,000)
Dividends paid to non-controlling interest			0
Employee benefit transactions			0
Income tax benefit arising from employee stock option			0
Purchase of common stock			0
Stock based compensation			0
Balance	1,085,400,000		1,085,400,000
Accumulated Other Comprehensive Income (Loss) [Member]
Balance			(51,200,000)
Consolidated net income			0
Other Comprehensive Income			(7,500,000)
Dividends declared			0
Dividends paid to non-controlling interest			0
Employee benefit transactions			0
Income tax benefit arising from employee stock option			0
Purchase of common stock			0
Stock based compensation			0
Balance	(58,700,000)		(58,700,000)
Treasury Stock [Member]
Balance			(541,900,000)
Consolidated net income			0
Other Comprehensive Income			0
Dividends declared			0
Dividends paid to non-controlling interest			0
Employee benefit transactions			0
Income tax benefit arising from employee stock option			0
Purchase of common stock			(44,000,000)
Stock based compensation			0
Balance	(585,900,000)		(585,900,000)
Noncontrolling Interest [Member]
Balance			23,300,000
Consolidated net income			2,200,000
Other Comprehensive Income			(1,400,000)
Dividends declared			0
Dividends paid to non-controlling interest			(800,000)
Employee benefit transactions			0
Income tax benefit arising from employee stock option			0
Purchase of common stock			0
Stock based compensation			0
Balance	$ 23,300,000		$ 23,300,000