Segment reporting (Summary of segment information) (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015 USD ($)	Oct. 03, 2015 USD ($)	Jul. 04, 2015 USD ($)	Apr. 04, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 27, 2014 USD ($)	Jun. 28, 2014 USD ($)	Mar. 29, 2014 USD ($)	Dec. 31, 2015 USD ($) segment	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Segment Reporting Information [Line Items]
Number of reporting segments | segment									3
Net sales	$ 1,997,997	$ 2,150,656	$ 2,041,733	$ 1,881,177	$ 1,951,446	$ 1,990,658	$ 2,048,247	$ 1,813,095	$ 8,071,563	$ 7,803,446	$ 7,348,754
Operating income (loss)									837,566	772,796	546,931
Depreciation and amortization									362,647	345,570	308,871
Capital expenditures (excluding acquisitions)									503,657	561,804	366,550
Assets	9,942,364				8,285,544				9,942,364	8,285,544	8,494,176
Long-lived assets	5,440,483				4,307,562				5,440,483	4,307,562	4,437,835
Soft Surface [Member]
Segment Reporting Information [Line Items]
Net sales									3,056,946	2,764,370	2,756,627
Tile [Member]
Segment Reporting Information [Line Items]
Net sales									3,094,389	3,087,895	2,744,289
Laminate and Wood [Member]
Segment Reporting Information [Line Items]
Net sales									1,920,228	1,951,181	1,847,838
United States [Member]
Segment Reporting Information [Line Items]
Net sales									5,399,561	5,233,796	5,083,605
Long-lived assets	2,945,783				2,381,843				2,945,783	2,381,843	2,186,946
Belgium [Member]
Segment Reporting Information [Line Items]
Long-lived assets	1,377,533				949,169				1,377,533	949,169	1,026,771
All other countries [Member]
Segment Reporting Information [Line Items]
Net sales									2,672,002	2,569,650	2,265,149
Long-lived assets	1,117,167				976,550				1,117,167	976,550	1,224,118
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization									9,543	10,682	11,524
Capital expenditures (excluding acquisitions)									11,783	9,276	8,817
Operating Segments [Member] | Global Ceramic [Member]
Segment Reporting Information [Line Items]
Net sales									3,012,859	3,015,279	2,677,058
Operating income (loss)									414,154	351,113	209,825
Depreciation and amortization									118,801	120,121	97,126
Capital expenditures (excluding acquisitions)									247,829	192,642	110,750
Assets	3,846,133				3,542,594				3,846,133	3,542,594	3,787,785
Operating Segments [Member] | Flooring NA [Member]
Segment Reporting Information [Line Items]
Net sales									3,602,112	3,441,018	3,423,093
Operating income (loss)									264,271	299,992	259,753
Depreciation and amortization									137,064	122,677	118,721
Capital expenditures (excluding acquisitions)									148,598	258,987	176,808
Assets	3,164,525				2,587,151				3,164,525	2,587,151	2,371,872
Operating Segments [Member] | Flooring ROW [Member]
Segment Reporting Information [Line Items]
Net sales									1,456,898	1,354,018	1,249,279
Operating income (loss)									203,370	151,528	107,850
Depreciation and amortization									97,239	92,090	81,500
Capital expenditures (excluding acquisitions)									95,447	100,899	70,175
Assets	2,805,246				1,909,487				2,805,246	1,909,487	2,115,152
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales									(306)	(6,869)	(676)
Corporate and Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating income (loss)									(44,229)	(29,837)	(30,497)
Assets	$ 126,460				$ 246,312				$ 126,460	$ 246,312	$ 219,367