Segment reporting (Summary of segment information) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 04, 2015 USD ($)	Jun. 28, 2014 USD ($)	Jul. 04, 2015 USD ($) segment	Jun. 28, 2014 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment			3
Segment Reporting Information [Line Items]
Net sales	$ 2,041,733	$ 2,048,247	$ 3,922,910	$ 3,861,342
Operating income (loss)	255,816	222,248	299,590	352,983
Assets	10,165,670		10,165,670		$ 8,285,544
Operating Segments [Member] | Global Ceramic Segment [Member]
Segment Reporting Information [Line Items]
Net sales	789,802	796,724	1,509,630	1,491,818
Operating income (loss)	121,189	106,407	206,516	167,066
Assets	3,950,088		3,950,088		3,542,594
Operating Segments [Member] | Flooring NA Segment [Member]
Segment Reporting Information [Line Items]
Net sales	920,337	895,912	1,767,248	1,676,243
Operating income (loss)	95,143	76,602	19,951	123,955
Assets	3,182,465		3,182,465		2,587,151
Operating Segments [Member] | Flooring ROW Segment [Member]
Segment Reporting Information [Line Items]
Net sales	331,622	357,738	646,364	695,804
Operating income (loss)	53,052	47,398	97,693	78,864
Assets	2,710,895		2,710,895		1,909,487
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment sales	(28)	(2,127)	(332)	(2,523)
Operating income (loss)	(13,568)	$ (8,159)	(24,570)	$ (16,902)
Assets	$ 322,222		$ 322,222		$ 246,312