REVENUE - Disaggregated Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Disaggregated revenue	$ 1,883	$ 1,818	$ 5,468	$ 5,333
Europe
Disaggregation of Revenue [Line Items]
Disaggregated revenue	310	304	920	909
Asia Pacific
Disaggregation of Revenue [Line Items]
Disaggregated revenue	169	166	492	484
Rest of world
Disaggregation of Revenue [Line Items]
Disaggregated revenue	131	140	386	415
Composites
Disaggregation of Revenue [Line Items]
Disaggregated revenue	531	508	1,579	1,560
Composites | Europe
Disaggregation of Revenue [Line Items]
Disaggregated revenue	142	142	442	455
Composites | Asia Pacific
Disaggregation of Revenue [Line Items]
Disaggregated revenue	120	115	351	343
Composites | Rest of world
Disaggregation of Revenue [Line Items]
Disaggregated revenue	35	32	97	97
Insulation
Disaggregation of Revenue [Line Items]
Disaggregated revenue	693	710	1,945	1,988
Insulation | Europe
Disaggregation of Revenue [Line Items]
Disaggregated revenue	165	159	469	444
Insulation | Asia Pacific
Disaggregation of Revenue [Line Items]
Disaggregated revenue	46	47	132	131
Insulation | Rest of world
Disaggregation of Revenue [Line Items]
Disaggregated revenue	77	83	215	236
Roofing
Disaggregation of Revenue [Line Items]
Disaggregated revenue	713	645	2,105	1,946
Roofing | Europe
Disaggregation of Revenue [Line Items]
Disaggregated revenue	3	3	10	10
Roofing | Asia Pacific
Disaggregation of Revenue [Line Items]
Disaggregated revenue	4	4	10	11
Roofing | Rest of world
Disaggregation of Revenue [Line Items]
Disaggregated revenue	19	26	77	88
Eliminations
Disaggregation of Revenue [Line Items]
Disaggregated revenue	(54)	(45)	(161)	(161)
Eliminations | Europe
Disaggregation of Revenue [Line Items]
Disaggregated revenue	0	0	(1)	0
Eliminations | Asia Pacific
Disaggregation of Revenue [Line Items]
Disaggregated revenue	(1)	0	(1)	(1)
Eliminations | Rest of world
Disaggregation of Revenue [Line Items]
Disaggregated revenue	0	(1)	(3)	(6)
Residential | U.S.
Disaggregation of Revenue [Line Items]
Disaggregated revenue	900	842	2,610	2,471
Residential | Composites | U.S.
Disaggregation of Revenue [Line Items]
Disaggregated revenue	75	62	217	213
Residential | Insulation | U.S.
Disaggregation of Revenue [Line Items]
Disaggregated revenue	237	260	649	708
Residential | Roofing | U.S.
Disaggregation of Revenue [Line Items]
Disaggregated revenue	641	560	1,900	1,696
Residential | Eliminations | U.S.
Disaggregation of Revenue [Line Items]
Disaggregated revenue	(53)	(40)	(156)	(146)
Commercial and Industrial Sector | U.S.
Disaggregation of Revenue [Line Items]
Disaggregated revenue	373	366	1,060	1,054
Commercial and Industrial Sector | Composites | U.S.
Disaggregation of Revenue [Line Items]
Disaggregated revenue	159	157	472	452
Commercial and Industrial Sector | Insulation | U.S.
Disaggregation of Revenue [Line Items]
Disaggregated revenue	168	161	480	469
Commercial and Industrial Sector | Roofing | U.S.
Disaggregation of Revenue [Line Items]
Disaggregated revenue	46	52	108	141
Commercial and Industrial Sector | Eliminations | U.S.
Disaggregation of Revenue [Line Items]
Disaggregated revenue	$ 0	$ (4)	$ 0	$ (8)