Note 16 - Reportable Segments - Reportable Segments (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Depreciation				$ 1,005	$ 1,041
Research, development, and engineering expenses (2)(3)		$ 251	$ 231	715	922
Income tax (provision) benefit		109	23	402	33
Net income attributable to Corning Incorporated		371	427	1,419	260
Operating Segments [Member]
Net sales of reportable segments and All Other		3,639	3,007	10,406	8,124
Depreciation	[1]	339	293	998	882
Research, development, and engineering expenses (2)(3)	[2]	218	177	605	567
Income tax (provision) benefit	[3]	(159)	(136)	(453)	(275)
Net income attributable to Corning Incorporated	[4]	593	504	1,701	1,028
Display Products [Member] | Operating Segments [Member]
Net sales of reportable segments and All Other		956	827	2,758	2,331
Depreciation	[1]	153	134	450	400
Research, development, and engineering expenses (2)(3)	[2]	31	22	79	77
Income tax (provision) benefit	[3]	(64)	(52)	(184)	(133)
Net income attributable to Corning Incorporated	[4]	247	196	708	500
Optical Communications [Member] | Operating Segments [Member]
Net sales of reportable segments and All Other		1,131	909	3,143	2,587
Depreciation	[1]	58	59	174	183
Research, development, and engineering expenses (2)(3)	[2]	57	50	160	157
Income tax (provision) benefit	[3]	(38)	(32)	(109)	(63)
Net income attributable to Corning Incorporated	[4]	139	115	398	225
Specialty Materials [Member] | Operating Segments [Member]
Net sales of reportable segments and All Other		556	570	1,490	1,339
Depreciation	[1]	42	40	125	120
Research, development, and engineering expenses (2)(3)	[2]	49	39	143	113
Income tax (provision) benefit	[3]	(28)	(38)	(74)	(76)
Net income attributable to Corning Incorporated	[4]	107	146	279	287
Environmental Technologies [Member] | Operating Segments [Member]
Net sales of reportable segments and All Other		385	379	1,233	925
Depreciation	[1]	34	32	105	99
Research, development, and engineering expenses (2)(3)	[2]	28	24	84	74
Income tax (provision) benefit	[3]	(16)	(18)	(57)	(27)
Net income attributable to Corning Incorporated	[4]	60	69	215	104
Life Science Products [Member] | Operating Segments [Member]
Net sales of reportable segments and All Other		305	223	917	724
Depreciation	[1]	14	12	40	37
Research, development, and engineering expenses (2)(3)	[2]	9	7	25	20
Income tax (provision) benefit	[3]	(12)	(8)	(39)	(26)
Net income attributable to Corning Incorporated	[4]	45	28	145	97
Other Segments [Member] | Operating Segments [Member]
Net sales of reportable segments and All Other		306	99	865	218
Depreciation	[1]	38	16	104	43
Research, development, and engineering expenses (2)(3)	[2]	44	35	114	126
Income tax (provision) benefit	[3]	(1)	12	10	50
Net income attributable to Corning Incorporated	[4]	$ (5)	$ (50)	$ (44)	$ (185)

[1] Depreciation expense for Corning's reportable segments includes an allocation of depreciation of corporate property not specifically identifiable to a segment.

[2] Research, development and engineering expenses include direct project spending that is identifiable to a segment.

[3] Income tax (provision) benefit reflects a tax rate of 21%.

[4] Many of Corning's administrative and staff functions are performed on a centralized basis. Where practicable, Corning charges these expenses to segments based upon the extent to which each business uses a centralized function. Other staff functions, such as corporate finance, human resources and legal, are allocated to segments, primarily as a percentage of sales. Expenses that are not allocated to the segments are included in the reconciliation of reportable segment net income (loss) to consolidated net income.