Goodwill and intangible assets (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Apr. 04, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill	$ 1,553,155us-gaap_Goodwill	$ 1,604,352us-gaap_Goodwill
Laminate and Wood Segment [Member]
Goodwill [Line Items]
Enterprise value	2,822
Goodwill	691,138	741,150
Unidentified Wood Business [Member] \| Laminate and Wood Segment [Member]
Goodwill [Line Items]
Goodwill	$ 2,659

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 30

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 30

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6613-128477

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration