Note 16 - Reportable Segments - Reconciliation of Reportable Segment Net Income (Loss) to Consolidated Net Income (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Net income attributable to Corning Incorporated		$ 371	$ 427		$ 1,419	$ 260
(Loss) gain on foreign currency hedges related to translated earnings		(13)	(100)		262	5
Research, development, and engineering expenses (2)(3)		251	231		715	922
Equity in earnings (losses) of affiliated companies (5)		16	(76)		31	17
Amortization of intangibles		(32)	(33)		(97)	(87)
Interest expense, net		(72)	(70)		(227)	(201)
Income tax benefit		(109)	(23)		(402)	(33)
Cumulative adjustment related to customer contract				$ (105)		105	[1]
Severance charges (3)						(141)
Asset impairment (3)			(22)			(217)
Operating Segments [Member]
Net income attributable to Corning Incorporated	[2]	593	504		1,701	1,028
Research, development, and engineering expenses (2)(3)	[3]	218	177		605	567
Income tax benefit	[4]	159	136		453	275
Operating Segments [Member] | Reportable Segments [Member]
Net income attributable to Corning Incorporated		598	554		1,745	1,213
Operating Segments [Member] | Nonreportable Segments [Member]
Net income attributable to Corning Incorporated	[5]	(5)	(50)		(44)	(185)
Segment Reconciling Items [Member]
Net income attributable to Corning Incorporated		371	427		1,419	260
Impact of foreign currency movements not included in segment net income (loss)		(33)			(47)	(25)
(Loss) gain on foreign currency hedges related to translated earnings		(13)	(99)		262	(6)
Translation gain (loss) on Japanese yen-denominated debt		4	(39)		127	(50)
Litigation, regulatory and other legal matters		(3)	(83)		(11)	(108)
Research, development, and engineering expenses (2)(3)	[6],[7]	(34)	(35)		(103)	(111)
Transaction-related gain, net (4)	[8]		498			498
Equity in earnings (losses) of affiliated companies (5)	[9]	10	(79)		9	20
Amortization of intangibles		(32)	(33)		(97)	(87)
Interest expense, net		(64)	(67)		(205)	(189)
Income tax benefit		50	113		51	242
Cumulative adjustment related to customer contract	[10]					(105)
Severance charges (3)	[7]	1	(6)			(141)
Asset impairment (3)	[7]		(22)			(217)
Capacity realignment and other charges and credits (3)	[7]	(41)	(143)		(42)	(375)
Gain on sale of a business					54
Other corporate items		$ (67)	$ (82)		$ (280)	$ (114)

[1] Amount represents the negative impact of a cumulative adjustment to reduce revenue by $105 million recorded during the first quarter of 2020. The adjustment was associated with a previously recorded commercial benefit asset, reflected as a prepayment, to a customer with a long-term supply agreement that substantially exited its production of LCD panels.

[2] 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.

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

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

[5] The Company obtained a controlling interest in HSG during the third quarter of 2020 and has consolidated results in "All Other" as of September 9, 2020.

[6] Amount does not include research, development, and engineering expense related to restructuring, impairment and other charges and credits.

[7] Refer to Note 2 (Restructuring, Impairment and Other Charges and Credits) to the consolidated financial statements for additional information on restructuring activities and impairment.

[8] Amount represents the pre-tax gain recorded on Corning's previously held equity investment in HSG. Refer to Note 3 (HSG Transactions) to the consolidated financial statements for additional information.

[9] Primarily represents the equity earnings of HSG prior to September 9, 2020. Refer to Note 3 (HSG Transactions) to the consolidated financial statements for additional information.

[10] Amount represents the negative impact of a cumulative adjustment to reduce revenue by $105 million recorded during the first quarter of 2020. The adjustment was associated with a previously recorded commercial benefit asset, reflected as a prepayment, to a customer with a long-term supply agreement that substantially exited its production of LCD panels.