COMMON STOCK AND EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Net earnings attributable to Knoll, Inc. stockholders	$ 15,404	$ 17,400
Weighted-average shares of common stock outstanding—basic (in shares)	48,456,225	47,904,593
Potentially dilutive shares resulting from stock plans (in shares)	927,000	689,000
Denominator for diluted earnings per share - weighted-average shares (in shares)	49,382,892	48,594,395
Antidilutive equity awards not included in weighted-average common shares—diluted (in shares)	12,000	0
Basic (in dollars per share)	$ 0.32	$ 0.36
Diluted (in dollars per share)	$ 0.31	$ 0.36