Noncontrolling interests (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jul. 01, 2012	Jun. 30, 2013	Jul. 01, 2012
Balance			$ 813,719,000
Consolidated net income	17,739,000	20,239,000	37,343,000	38,847,000
Other Comprehensive Income			(18,300,000)
Dividends declared			(3,500,000)
Dividends paid to non-controlling interest			(763,000)	(3,249,000)
Employee benefit transactions			4,600,000
Income tax benefit arising from employee stock option			800,000
Purchase of common stock			(20,100,000)
Stock based compensation			1,800,000
Balance	815,555,000		815,555,000
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			0
Income tax benefit arising from employee stock option			0
Purchase of common stock			0
Stock based compensation			0
Balance	4,700,000		4,700,000
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			4,600,000
Income tax benefit arising from employee stock option			800,000
Purchase of common stock			0
Stock based compensation			1,800,000
Balance	353,200,000		353,200,000
Retained Earnings [Member]
Balance			1,032,900,000
Consolidated net income			35,900,000
Other Comprehensive Income			0
Dividends declared			(3,500,000)
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	1,065,200,000		1,065,200,000
Accumulated Other Comprehensive Income (Loss) [Member]
Balance			(51,200,000)
Consolidated net income			0
Other Comprehensive Income			(17,000,000)
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	(68,200,000)		(68,200,000)
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			(20,100,000)
Stock based compensation			0
Balance	(562,000,000)		(562,000,000)
Noncontrolling Interest [Member]
Balance			23,300,000
Consolidated net income			1,500,000
Other Comprehensive Income			(1,300,000)
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	$ 22,700,000		$ 22,700,000