CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Sales	$ 356.5	$ 327.7	$ 1,056.6	$ 947.6
Cost of sales	216.1	204.9	651.7	597.8
Gross profit	140.4	122.8	404.9	349.8
Selling, general, and administrative expenses	103.6	88.7	304.9	267.0
Restructuring charges	0.1	1.2	0.2	2.6
Operating profit	36.7	32.9	99.8	80.2
Interest expense	5.5	5.0	16.2	14.4
Loss on extinguishment of debt	0.4	0.0	0.4	1.4
Pension settlement charge	9.8	0.6	10.4	5.2
Other income, net	(2.5)	(0.2)	(4.1)	(7.0)
Income before income tax expense	23.5	27.5	76.9	66.2
Income tax expense	6.0	7.2	19.8	17.5
Net earnings	$ 17.5	$ 20.3	$ 57.1	$ 48.7
Net earnings per common share attributable to Knoll, Inc. stockholders:
Basic (in dollars per share)	$ 0.36	$ 0.42	$ 1.17	$ 1.00
Diluted (in dollars per share)	0.35	0.41	1.16	0.99
Dividends per share (in dollars per share)	$ 0.17	$ 0.15	$ 0.49	$ 0.45
Weighted-average number of common shares outstanding:
Basic (in shares)	48,873,186	48,694,438	48,834,737	48,641,595
Diluted (in shares)	49,573,706	49,231,376	49,359,812	49,189,592
Other comprehensive income (loss):
Unrealized gain (loss) on interest rate swap, net of tax and amounts reclassified into earnings	$ (0.4)	$ 0.9	$ (4.7)	$ 2.0
Pension and other post-employment liability adjustment, net of tax	(2.5)	1.1	(2.0)	9.0
Foreign currency translation adjustment	(4.0)	(4.6)	(1.7)	(10.9)
Foreign currency translation adjustment on long term intercompany notes	(7.1)	3.1	(9.2)	(2.5)
Total other comprehensive income (loss), net of tax	(14.0)	0.5	(17.6)	(2.4)
Total comprehensive income	$ 3.5	$ 20.8	$ 39.5	$ 46.3