Goodwill and intangible assets (Schedule of goodwill) (Details) $ in Thousands	6 Months Ended
	Jul. 04, 2015 USD ($)
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	$ 2,931,777
Accumulated impairment losses	(1,327,425)
Goodwill, net, beginning balance	1,604,352
Goodwill recognized or adjusted during the period	740,766
Currency translation during the year	(50,904)
Goodwill, gross, ending balance	3,621,639
Accumulated impairment losses	(1,327,425)
Goodwill, net, ending balance	2,294,214
Global Ceramic Segment [Member]
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	1,395,132
Accumulated impairment losses	(531,930)
Goodwill, net, beginning balance	863,202
Goodwill recognized or adjusted during the period	100,048
Currency translation during the year	(106)
Goodwill, gross, ending balance	1,495,074
Accumulated impairment losses	(531,930)
Goodwill, net, ending balance	963,144
Flooring NA Segment [Member]
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	538,515
Accumulated impairment losses	(343,054)
Goodwill, net, beginning balance	195,461
Goodwill recognized or adjusted during the period	329,401
Currency translation during the year	0
Goodwill, gross, ending balance	867,916
Accumulated impairment losses	(343,054)
Goodwill, net, ending balance	524,862
Flooring ROW Segment [Member]
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	998,130
Accumulated impairment losses	(452,441)
Goodwill, net, beginning balance	545,689
Goodwill recognized or adjusted during the period	311,317
Currency translation during the year	(50,798)
Goodwill, gross, ending balance	1,258,649
Accumulated impairment losses	(452,441)
Goodwill, net, ending balance	$ 806,208