Product warranties (Provision for warranty obligations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 29, 2014	Mar. 30, 2013	Mar. 31, 2012
Product Warranties Disclosures [Abstract]
Product warranty period, maximum	50 years
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of period	$ 35,818		$ 32,930
Warranty claims paid during the period	(14,024)	(13,301)
Acquisitions	0	2,780
Warranty expense during the period	11,466	13,074
Balance at end of period	$ 33,260	$ 35,483	$ 32,930