Acquisitions, Goodwill And Other Intangible Assets (Schedule of Business Acquisitions) (Details) - USD ($) $ in Thousands			1 Months Ended								12 Months Ended
	Jun. 30, 2017	Feb. 01, 2017	May 31, 2017	Nov. 30, 2016	May 31, 2016	Feb. 29, 2016	Jan. 31, 2016	Aug. 31, 2015	Apr. 30, 2015	Jan. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	May 01, 2017	Apr. 30, 2014
Business Acquisition
Cash consideration, net of cash acquired											$ 60,588	$ 48,725	$ 41,058
Goodwill (tax deductible)											$ 124,183	89,198	$ 83,619
Sessa Klein S.p.A.
Business Acquisition
Cash consideration, net of cash acquired		$ 6,502
Cash consideration		8,500
Contingent consideration		4,922
Total fair value of consideration given		11,424
Net tangible assets		585
Total fair value of net assets acquired		5,103
Goodwill (tax deductible)		6,321
Metallarte S.r.l.
Business Acquisition
Cash consideration, net of cash acquired	$ 13,501
Cash consideration	14,100
Contingent consideration	2,366
Total fair value of consideration given	15,867
Net other liabilities	(320)
Total fair value of net assets acquired	8,830
Goodwill (tax deductible)	7,037
Lexington
Business Acquisition
Cash consideration			$ 40,062
Total fair value of consideration given			$ 40,100
Net tangible assets														$ 4,928
Total fair value of net assets acquired														23,648
Goodwill (tax deductible)														16,414
Flair Interiors
Business Acquisition
Cash consideration						$ 8,100
Net other assets						2,378
Total fair value of net assets acquired						6,078
Goodwill (tax deductible)						2,022
Highwater
Business Acquisition
Cash consideration							$ 10,000
Net tangible assets							1,307
Total fair value of net assets acquired							9,407
Goodwill (tax deductible)							593
Atwood Mobile Products, LLC
Business Acquisition
Cash consideration				$ 12,463
Total fair value of consideration given				12,500
Net other assets				10,915
Total fair value of net assets acquired				12,415
Project 2000
Business Acquisition
Cash consideration, net of cash acquired					$ 16,618
Cash consideration					18,800
Contingent consideration					1,322
Total fair value of consideration given					17,940
Net other liabilities					(3,482)
Total fair value of net assets acquired					12,355
Goodwill (tax deductible)					5,585
Signature Seating
Business Acquisition
Cash consideration								$ 16,000
Contingent consideration								3,556
Total fair value of consideration given								19,556
Net other assets								4,023
Total fair value of net assets acquired								11,523
Goodwill (tax deductible)								8,033
Spectal Industries, Inc.
Business Acquisition
Cash consideration									$ 22,335
Contingent consideration									1,211
Total fair value of consideration given									$ 23,546
Net other assets															$ 4,381
Total fair value of net assets acquired															14,481
Goodwill (tax deductible)															9,065
EA Technologies, LLC
Business Acquisition
Cash consideration										$ 9,248		$ 6,600
Total fair value of consideration given										9,200
Net tangible assets										8,868
Total fair value of net assets acquired										9,348
Gain on bargain purchase										100
Customer Relationships | Sessa Klein S.p.A.
Business Acquisition
Identifiable intangible assets		3,189
Customer Relationships | Metallarte S.r.l.
Business Acquisition
Identifiable intangible assets	7,000
Customer Relationships | Lexington
Business Acquisition
Identifiable intangible assets														16,900
Customer Relationships | Flair Interiors
Business Acquisition
Identifiable intangible assets						$ 3,700
Customer Relationships | Highwater
Business Acquisition
Identifiable intangible assets							$ 8,100
Customer Relationships | Atwood Mobile Products, LLC
Business Acquisition
Identifiable intangible assets				$ 1,500
Customer Relationships | Project 2000
Business Acquisition
Identifiable intangible assets					9,696
Customer Relationships | Signature Seating
Business Acquisition
Identifiable intangible assets								$ 7,500
Customer Relationships | Spectal Industries, Inc.
Business Acquisition
Identifiable intangible assets															$ 10,100
Other Identifiable Intangible Assets | Sessa Klein S.p.A.
Business Acquisition
Identifiable intangible assets		$ 1,329
Other Identifiable Intangible Assets | Metallarte S.r.l.
Business Acquisition
Identifiable intangible assets	$ 2,150
Other Identifiable Intangible Assets | Lexington
Business Acquisition
Identifiable intangible assets														$ 1,820
Other Identifiable Intangible Assets | Project 2000
Business Acquisition
Identifiable intangible assets					$ 6,141
Other Identifiable Intangible Assets | EA Technologies, LLC
Business Acquisition
Identifiable intangible assets										$ 480