EQUITY (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			$ 309,469
Net earnings	$ 19,161	$ 21,618	47,513	$ 60,670
Other comprehensive income	5,737	$ (1,917)	8,262	$ 3,427
Exercise of stock options (22,500 shares)			472
Shares issued under stock incentive plan (678,399 shares)			4
Shares issued to Board of Directors in lieu of cash (4,438 shares)			100
Stock-based compensation, net of forfeitures (57,911 shares)			7,314
Cash dividend ($0.45 per share)			(22,455)
Purchase of common stock (419,890 shares)			(10,570)
Ending Balance	340,109		$ 340,109
Exercise of stock options (in shares)			22,500
Shares issued under stock incentive plan (676,850) (in shares)			678,399
Shares issued to Board of Directors in lieu of cash (in shares)			4,438
Cash dividend (in dollars per share)			$ 0.45
Purchase of common stock (in shares)			419,890
Total Knoll, Inc. Stockholders' Equity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			$ 309,247
Net earnings			47,470
Other comprehensive income			8,262
Exercise of stock options (22,500 shares)			472
Shares issued under stock incentive plan (678,399 shares)			4
Shares issued to Board of Directors in lieu of cash (4,438 shares)			100
Stock-based compensation, net of forfeitures (57,911 shares)			7,314
Cash dividend ($0.45 per share)			(22,455)
Purchase of common stock (419,890 shares)			(10,570)
Ending Balance	339,844		339,844
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			491
Shares issued under stock incentive plan (678,399 shares)			7
Stock-based compensation, net of forfeitures (57,911 shares)			1
Purchase of common stock (419,890 shares)			(4)
Ending Balance	493		493
Additional Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			55,148
Exercise of stock options (22,500 shares)			472
Shares issued under stock incentive plan (678,399 shares)			(3)
Shares issued to Board of Directors in lieu of cash (4,438 shares)			100
Stock-based compensation, net of forfeitures (57,911 shares)			7,315
Purchase of common stock (419,890 shares)			(10,566)
Ending Balance	52,466		52,466
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			297,011
Net earnings			47,470
Cash dividend ($0.45 per share)			(22,455)
Ending Balance	322,026		322,026
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			(43,403)
Other comprehensive income			8,262
Ending Balance	(35,141)		(35,141)
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			222
Net earnings			43
Ending Balance	$ 265		$ 265