QUARTERLY RESULTS (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Sales	$ 305,734	$ 263,588	$ 268,622	$ 266,498	$ 286,453	$ 268,297	$ 265,943	$ 229,601	$ 1,104,442	$ 1,050,294	$ 862,252
Gross profit	114,425	101,207	101,191	95,309	102,850	94,962	97,274	76,598	412,132	371,685	280,332
Net earnings	13,430	17,861	17,222	17,435	12,316	15,597	10,841	7,832	65,948	46,585	23,184
Net earnings attributable to Knoll, Inc. stockholders	$ 13,448	$ 17,833	$ 17,239	$ 17,443	$ 12,288	$ 15,628	$ 10,855	$ 7,826	$ 65,963	$ 46,596	$ 23,184
Earnings per share—Basic (in dollars per share)	$ 0.28	$ 0.37	$ 0.36	$ 0.37	$ 0.26	$ 0.33	$ 0.23	$ 0.17	$ 1.38	$ 0.98	$ 0.49
Earnings per share—Diluted (in dollars per share)	$ 0.28	$ 0.37	$ 0.36	$ 0.36	$ 0.26	$ 0.33	$ 0.23	$ 0.16	$ 1.36	$ 0.97	$ 0.49
Asset Impairment Charges	$ 10,700
Restructuring and other charges	$ 500	$ 400			$ 700		$ 200	$ 600	$ 896	$ 1,532	$ 5,104
Loss of settlement and curtailment					$ 6,500				$ (7,100)