COMMON STOCK AND EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net earnings attributable to Knoll, Inc. stockholders	$ 21,298	$ 17,239	$ 38,556	$ 34,682
Denominator for basic earnings per share - weighted-average shares	48,018,733	47,760,961	47,961,661	47,705,222
Potentially dilutive shares resulting from stock plans (in shares)	645,000	749,000	627,000	740,000
Denominator for diluted earnings per share - weighted-average shares (in shares)	48,664,318	48,509,546	48,588,725	48,445,060
Antidilutive equity awards not included in weighted-average common shares—diluted (in shares)	0	0	0	0
Basic (in dollars per share)	$ 0.44	$ 0.36	$ 0.80	$ 0.73
Diluted (in dollars per share)	$ 0.44	$ 0.36	$ 0.79	$ 0.72