Share repurchase program (Details Textuals) (USD $)	1 Months Ended	3 Months Ended
	Aug. 31, 2011	Sep. 29, 2012
Share Repurchase Program [Abstract]
Authorized repurchase of common stock under Share Repurchase Program	$ 500,000,000	$ 750,000,000
Stock Repurchase Program, authorized additional amount		250,000,000
Shares repurchased during period		4,170,000
Average market price per shares repurchased during period		$ 31.34
Cost of repurchase		130,685,000
Stock Repurchase Program, Aggregate Number of Shares Repurchased Since Inception		15,440,000
Stock Repurchase Program, Aggregate Cost of Shares Repurchased Since Inception		$ 456,625,000