CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Sales	$ 332.8	$ 296.6
Cost of sales	209.0	188.9
Gross profit	123.8	107.7
Selling, general, and administrative expenses	94.5	84.7
Restructuring charges	0.1	0.5
Operating profit	29.2	22.5
Interest expense	5.2	4.1
Loss on extinguishment of debt	0.0	1.4
Pension settlement charge	0.2	0.0
Other income, net	(0.7)	(4.0)
Income before income tax expense	24.5	21.0
Income tax expense	6.5	5.7
Net earnings	$ 18.0	$ 15.3
Net earnings per common share attributable to Knoll, Inc. stockholders:
Basic (in dollars per share)	$ 0.37	$ 0.31
Diluted (in dollars per share)	0.37	0.31
Dividends per share (in dollars per share)	$ 0.15	$ 0.15
Weighted-average number of common shares outstanding:
Basic (in shares)	48,774,883	48,556,686
Diluted (in shares)	49,190,288	49,204,776
Other comprehensive income (loss):
Unrealized loss on interest rate swap, net of tax	$ (1.5)	$ (0.1)
Pension and other post-employment liability adjustment, net of tax	0.1	0.2
Foreign currency translation adjustment	1.9	(0.4)
Foreign currency translation adjustment on long term intercompany notes	(4.1)	(0.5)
Total other comprehensive (loss), net of tax	(3.6)	(0.8)
Total comprehensive income	$ 14.4	$ 14.5