CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Sales	$ 367.3	$ 323.4	$ 700.1	$ 619.9
Cost of sales	226.6	204.2	435.6	392.9
Gross profit	140.7	119.2	264.5	227.0
Selling, general, and administrative expenses	106.8	93.6	201.3	178.4
Restructuring charges	0.0	0.8	0.1	1.4
Operating profit	33.9	24.8	63.1	47.2
Interest expense	5.5	5.3	10.7	9.3
Loss on extinguishment of debt	0.0	0.0	0.0	1.4
Pension settlement charge	0.5	4.6	0.6	4.6
Other income, net	(1.0)	(2.8)	(1.6)	(6.8)
Income before income tax expense	28.9	17.7	53.4	38.7
Income tax expense	7.2	4.6	13.8	10.3
Net earnings	$ 21.7	$ 13.1	$ 39.6	$ 28.4
Net earnings per common share attributable to Knoll, Inc. stockholders:
Basic (in dollars per share)	$ 0.44	$ 0.27	$ 0.81	$ 0.58
Diluted (in dollars per share)	0.44	0.27	0.80	0.58
Dividends per share (in dollars per share)	$ 0.17	$ 0.15	$ 0.32	$ 0.30
Weighted-average number of common shares outstanding:
Basic (in shares)	48,855,064	48,672,144	48,815,194	48,614,733
Diluted (in shares)	49,314,364	49,131,106	49,252,546	49,137,528
Other comprehensive income (loss):
Unrealized (loss) gain on interest rate swap, net of tax	$ (2.8)	$ 1.2	$ (4.3)	$ 1.1
Pension and other post-employment liability adjustment, net of tax	0.4	7.7	0.5	7.9
Foreign currency translation adjustment	0.4	(6.0)	2.3	(6.3)
Foreign currency translation adjustment on long term intercompany notes	2.0	(5.1)	(2.1)	(5.6)
Total other comprehensive income (loss), net of tax	0.0	(2.2)	(3.6)	(2.9)
Total comprehensive income	$ 21.7	$ 10.9	$ 36.0	$ 25.5