Income taxes (Details) (USD $)	3 Months Ended		6 Months Ended
	Dec. 31, 2011	Jan. 01, 2011	Dec. 31, 2011	Jan. 01, 2011
Income taxes (Textuals) [Abstract]
Effective tax rate	29.30%	30.50%	29.20%	31.50%
Income tax adjustment				$ 16,900,000