EQUITY (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Change in equity attributable to Knoll, Inc. stockholders and noncontrolling interests:
Balance, as of December 31, 2014			$ 213,218
Total comprehensive income:
Net earnings attributable to Knoll, Inc. stockholders and noncontrolling interests			52,518	$ 34,270
Total other comprehensive income (loss), net of tax	$ 674	$ (7,424)	(9,443)	$ (7,386)
Other changes in equity:
Purchase of common stock for treasury			(7,478)
Cash dividends declared			(17,684)
Proceeds from the issuance of common stock			5,247
Stock-based compensation			5,650
Excess tax benefit from the exercise of stock options and vesting of equity awards			940
Balance, as of September 30, 2015	242,968		242,968
Equity Attributable to Knoll Inc., Stockholders
Change in equity attributable to Knoll, Inc. stockholders and noncontrolling interests:
Balance, as of December 31, 2014			213,011
Total comprehensive income:
Net earnings attributable to Knoll, Inc. stockholders and noncontrolling interests			52,515
Total other comprehensive income (loss), net of tax			(9,443)
Other changes in equity:
Purchase of common stock for treasury			(7,478)
Cash dividends declared			(17,684)
Proceeds from the issuance of common stock			5,247
Stock-based compensation			5,650
Excess tax benefit from the exercise of stock options and vesting of equity awards			940
Balance, as of September 30, 2015	242,758		242,758
Noncontrolling Interests
Change in equity attributable to Knoll, Inc. stockholders and noncontrolling interests:
Balance, as of December 31, 2014			207
Total comprehensive income:
Net earnings attributable to Knoll, Inc. stockholders and noncontrolling interests			3
Total other comprehensive income (loss), net of tax			0
Other changes in equity:
Purchase of common stock for treasury			0
Cash dividends declared			0
Proceeds from the issuance of common stock			0
Stock-based compensation			0
Excess tax benefit from the exercise of stock options and vesting of equity awards			0
Balance, as of September 30, 2015	$ 210		$ 210