Goodwill and intangible assets - Schedule of goodwill (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2018	Jun. 30, 2018
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	$ 3,798,884	$ 3,798,884
Accumulated impairment losses	(1,327,425)	(1,327,425)
Goodwill, net, beginning balance	2,471,459	2,471,459
Goodwill recognized during the period		12,548
Currency translation during the period		(36,961)
Goodwill, gross, ending balance		3,774,471
Accumulated impairment losses		(1,327,425)
Goodwill, net, ending balance		2,447,046
Global Ceramic segment
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	1,567,872	1,567,872
Accumulated impairment losses	(531,930)	(531,930)
Goodwill, net, beginning balance	1,035,942	1,035,942
Goodwill recognized during the period		0
Currency translation during the period		(11,342)
Goodwill, gross, ending balance		1,556,530
Accumulated impairment losses		(531,930)
Goodwill, net, ending balance		1,024,600
Flooring NA segment
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	869,764	869,764
Accumulated impairment losses	(343,054)	(343,054)
Goodwill, net, beginning balance	526,710	526,710
Goodwill recognized during the period		0
Currency translation during the period		0
Goodwill, gross, ending balance		869,764
Accumulated impairment losses		(343,054)
Goodwill, net, ending balance		526,710
Flooring ROW segment
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	1,361,248	1,361,248
Accumulated impairment losses	(452,441)	(452,441)
Goodwill, net, beginning balance	908,807	908,807
Goodwill recognized during the period	$ 12,548	12,548
Currency translation during the period		(25,619)
Goodwill, gross, ending balance		1,348,177
Accumulated impairment losses		(452,441)
Goodwill, net, ending balance		$ 895,736