COMMON STOCK AND EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Net earnings attributable to Knoll, Inc. stockholders	$ 17,259	$ 17,443
Weighted-average shares of common stock outstanding—basic (in shares)	47,904,593	47,647,961
Potentially dilutive shares resulting from stock plans (in shares)	666,000	705,000
Weighted-average common shares—diluted (in shares)	48,570,895	48,353,047
Antidilutive equity awards not included in weighted-average common shares—diluted (in shares)	0	0
Basic (in dollars per share)	$ 0.36	$ 0.37
Diluted (in dollars per share)	$ 0.36	$ 0.36