ACQUISITIONS - Pro forma Summary Financial Information (Details) (Holly Hunt Enterprises, Inc [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Holly Hunt Enterprises, Inc [Member]
Business Acquisition, Pro Forma Information [Abstract]
Pro forma net sales	$ 237,152	$ 222,010
Pro forma net earnings attributable to Knoll, Inc stockholders	$ 8,612	$ 6,468
Pro forma basic earnings per share attributable to Knoll, Inc. stockholders (in dollars per share)	$ 0.18	$ 0.14
Pro forma dilutive earnings per share attributable to Knoll, Inc. stockholders (in dollars per share)	$ 0.18	$ 0.14