CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Sales	$ 296,559	$ 256,820
Cost of sales	188,848	161,146
Gross profit	107,711	95,674
Selling, general, and administrative expenses	84,725	75,038
Restructuring charges	526	0
Operating profit	22,460	20,636
Interest expense	4,083	1,671
Loss on extinguishment of debt	1,445	0
Other income, net	(4,002)	(2,195)
Income before income tax expense	20,934	21,160
Income tax expense	5,667	5,764
Net earnings	15,267	15,396
Net earnings (loss) attributable to noncontrolling interests	8	(8)
Net earnings	$ 15,259	$ 15,404
Net earnings per common share attributable to Knoll, Inc. stockholders:
Basic (in dollars per share)	$ 0.31	$ 0.32
Diluted (in dollars per share)	0.31	0.31
Dividends per share (in dollars per share)	$ 0.15	$ 0.15
Weighted-average number of common shares outstanding:
Basic (in shares)	48,556,686	48,456,225
Diluted (in shares)	49,204,776	49,382,892
Other comprehensive income (loss):
Unrealized loss on interest rate swap, net of tax	$ (130)	$ 0
Pension and other post-employment liability adjustment, net of tax	211	(137)
Foreign currency translation adjustment	(339)	480
Foreign currency translation adjustment on long term intercompany notes	(507)	0
Total other comprehensive (loss) income, net of tax	(765)	343
Total comprehensive income	14,502	15,739
Comprehensive income attributable to noncontrolling interests	8	(8)
Comprehensive income attributable to Knoll, Inc. stockholders	$ 14,494	$ 15,747