QUARTERLY RESULTS (UNAUDITED) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cost of sales		$ 173,335,000	$ 168,669,000	$ 153,003,000	$ 156,221,000	$ 144,559,000	$ 144,431,000	$ 136,709,000	$ 678,609,000	$ 581,920,000	$ 600,602,000
Selling, general, and administrative expenses		71,647,000	74,833,000	64,722,000	58,425,000	55,485,000	57,276,000	53,729,000	286,801,000	224,915,000	206,422,000
Restructuring and other charges	700,000		203,000	592,000	5,104,000		0	0	1,532,000	5,104,000	0
Operating profit		23,315,000	22,238,000	11,284,000	1,806,000	16,854,000	12,605,000	10,148,000	76,843,000	41,413,000	91,472,000
Interest expense		1,899,000	1,944,000	1,671,000	1,445,000	1,484,000	1,517,000	1,495,000	7,378,000	5,941,000	6,350,000
Nonoperating Income (Expense)		3,294,000	(2,700,000)	2,504,000	2,157,000	(2,224,000)	2,206,000	1,291,000	6,285,000	3,430,000	(3,215,000)
Income before income tax expense		24,710,000	17,594,000	12,117,000	2,518,000	13,146,000	13,294,000	9,944,000	75,750,000	38,902,000	81,907,000
Income tax expense		9,113,000	6,753,000	4,285,000	1,772,000	4,916,000	5,481,000	3,549,000	29,165,000	15,718,000	30,384,000
Net earnings	12,316,000	15,597,000	10,841,000	7,832,000	746,000	8,230,000	7,813,000	6,395,000	46,585,000	23,184,000	51,523,000
Net loss attributable to noncontrolling interests		(31,000)	(14,000)	6,000	0	0	0	0	(11,000)	0	0
Net earnings attributable to Knoll, Inc. stockholders	12,288,000	15,628,000	10,855,000	7,826,000	746,000	8,230,000	7,813,000	6,395,000	46,596,000	23,184,000	51,523,000
Sales	286,453,000	268,297,000	265,943,000	229,601,000	230,456,000	216,898,000	214,312,000	200,586,000	1,050,294,000	862,252,000	898,496,000
Gross profit	102,850,000	94,962,000	97,274,000	76,598,000	74,235,000	72,339,000	69,881,000	63,877,000	371,685,000	280,332,000	297,894,000
Earnings per share - Basic (in dollars per share)	$ 0.26	$ 0.33	$ 0.23	$ 0.17	$ 0.02	$ 0.18	$ 0.17	$ 0.14	$ 0.98	$ 0.49	$ 1.10
Diluted (in dollars per share)	$ 0.26	$ 0.33	$ 0.23	$ 0.16	$ 0.02	$ 0.17	$ 0.16	$ 0.13	$ 0.97	$ 0.49	$ 1.09
Loss of settlement and curtailment	6,500,000
Intangible asset impairment charge					8,900,000				0	8,900,000	0
Restructuring charges					5,100,000				2,517,000	5,104,000
As previously reported
Cost of sales		173,335,000	168,594,000	152,856,000	156,443,000	144,559,000	144,431,000	136,959,000		582,393,000	593,149,000
Selling, general, and administrative expenses		71,647,000	74,805,000	64,650,000	58,525,000	55,288,000	57,473,000	53,333,000		224,619,000	206,449,000
Restructuring and other charges			203,000	0	5,696,000		0	0		5,696,000	0
Operating profit		23,315,000	22,195,000	11,825,000	1,308,000	17,051,000	12,408,000	10,294,000		41,060,000	87,901,000
Interest expense		1,899,000	1,944,000	1,671,000	1,445,000	1,484,000	1,517,000	1,495,000		5,941,000	6,350,000
Nonoperating Income (Expense)		3,294,000	(2,700,000)	2,504,000	2,157,000	(2,224,000)	2,206,000	1,291,000		3,430,000	(3,215,000)
Income before income tax expense		24,710,000	17,551,000	12,658,000	2,020,000	13,343,000	13,097,000	10,090,000		38,549,000	78,336,000
Income tax expense		9,088,000	6,712,000	4,466,000	1,386,000	4,793,000	5,209,000	4,016,000		15,403,000	28,335,000
Net earnings		15,622,000	10,839,000	8,192,000	634,000	8,550,000	7,888,000	6,074,000		23,146,000	50,001,000
Net loss attributable to noncontrolling interests		(31,000)	(14,000)	6,000	0	0	0	0
Net earnings attributable to Knoll, Inc. stockholders		15,653,000	10,853,000	8,186,000	634,000	8,550,000	7,888,000	6,074,000		23,146,000	50,001,000
Sales		268,297,000	265,797,000	229,331,000	230,872,000	216,898,000	214,312,000	200,586,000		862,668,000	887,499,000
Gross profit		94,962,000	97,203,000	76,475,000	74,429,000	72,339,000	69,881,000	63,627,000		280,275,000	294,350,000
Earnings per share - Basic (in dollars per share)		$ 0.33	$ 0.23	$ 0.17	$ 0.01	$ 0.18	$ 0.17	$ 0.13		$ 0.49	$ 1.07
Diluted (in dollars per share)		$ 0.33	$ 0.23	$ 0.17	$ 0.01	$ 0.18	$ 0.17	$ 0.13		$ 0.49	$ 1.06
Intangible asset impairment charge					8,900,000					8,900,000	0
Correction of prior period misstatements
Cost of sales		0	75,000	147,000	(222,000)	0	0	(250,000)		(473,000)	7,453,000
Selling, general, and administrative expenses		0	28,000	72,000	(100,000)	197,000	(197,000)	396,000		296,000	(27,000)
Restructuring and other charges			0	592,000	(592,000)		0	0		(592,000)	0
Operating profit		0	43,000	(541,000)	498,000	(197,000)	197,000	(146,000)		353,000	3,571,000
Interest expense		0	0	0	0	0	0	0		0	0
Nonoperating Income (Expense)		0	0	0	0	0	0	0		0	0
Income before income tax expense		0	43,000	(541,000)	498,000	(197,000)	197,000	(146,000)		353,000	3,571,000
Income tax expense		25,000	41,000	(181,000)	386,000	123,000	272,000	(467,000)		315,000	2,049,000
Net earnings		(25,000)	2,000	(360,000)	112,000	(320,000)	(75,000)	321,000		38,000	1,522,000
Net loss attributable to noncontrolling interests		0	0	0	0	0	0	0
Net earnings attributable to Knoll, Inc. stockholders		(25,000)	2,000	(360,000)	112,000	(320,000)	(75,000)	321,000		38,000	1,522,000
Sales		0	146,000	270,000	(416,000)	0	0	0		(416,000)	10,997,000
Gross profit		0	71,000	123,000	(194,000)	0	0	250,000		57,000	3,544,000
Earnings per share - Basic (in dollars per share)		$ 0.00	$ 0.00	$ 0.00	$ 0.01	$ 0.00	$ 0.00	$ 0.01		$ 0.00	$ 0.03
Diluted (in dollars per share)		$ 0.00	$ 0.00	$ (0.01)	$ 0.01	$ (0.01)	$ (0.01)	$ 0.00		$ 0.00	$ 0.03
Intangible asset impairment charge					$ 0					$ 0	$ 0