EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Net earnings attributable to Knoll, Inc. stockholders	$ 13,448	$ 17,833	$ 17,239	$ 17,443	$ 12,288	$ 15,628	$ 10,855	$ 7,826	$ 65,963	$ 46,596	$ 23,184
Weighted-average shares of common stock outstanding—basic (in shares)									47,746,707	47,346,532	46,916,845
Potentially dilutive shares resulting from stock plans (in shares)									691,000	721,000	742,000
Weighted-average common shares—diluted (in shares)									48,438,231	48,068,249	47,659,418
Antidilutive equity awards not included in weighted-average common shares—diluted (in shares)									4,000	144,000	164,000
Basic (in dollars per share)	$ 0.28	$ 0.37	$ 0.36	$ 0.37	$ 0.26	$ 0.33	$ 0.23	$ 0.17	$ 1.38	$ 0.98	$ 0.49
Diluted (in dollars per share)	$ 0.28	$ 0.37	$ 0.36	$ 0.36	$ 0.26	$ 0.33	$ 0.23	$ 0.16	$ 1.36	$ 0.97	$ 0.49