Note 16 - Reportable Segments - Reconciliation of Reportable Segment Net Income (Loss) to Consolidated Net Income (Details) - USD ($) $ in Millions		3 Months Ended					6 Months Ended				12 Months Ended
		Jun. 30, 2021		Jun. 30, 2020		Mar. 31, 2020	Jun. 30, 2021		Jun. 30, 2020		Dec. 31, 2020
Net income (loss) attributable to Corning Incorporated		$ 449		$ (71)			$ 1,048		$ (167)
Gain on foreign currency hedges related to translated earnings		3		37			275		105
Research, development, and engineering expenses		(242)		(430)			(464)		(691)
Equity in (losses) earnings of affiliated companies		7		79			15		93
Amortization of intangibles		(33)		(28)			(65)		(54)
Interest expense, net		(78)		(67)			(155)		(131)
Income tax benefit		(67)		(22)			(293)		(10)
Cumulative adjustment related to customer contract			[1]		[1]	$ 105		[1]	105	[1]
Severance charges				(58)			(1)		(135)
Asset impairment				(195)					(195)		$ (217)
Operating Segments [Member]
Net income (loss) attributable to Corning Incorporated	[2]	595		288			1,108		524
Research, development, and engineering expenses	[3]	(200)		(181)			(387)		(390)
Income tax benefit	[4]	158		77			294		139
Operating Segments [Member] | Reportable Segments [Member]
Net income (loss) attributable to Corning Incorporated		610		354			1,147		659
Operating Segments [Member] | Nonreportable Segments [Member]
Net income (loss) attributable to Corning Incorporated	[5]	(15)		(66)			(39)		(135)
Segment Reconciling Items [Member]
Impact of foreign currency movements not included in segment net income (loss)		(20)		(6)			(14)		(25)
Gain on foreign currency hedges related to translated earnings		3		35			275		93
Translation gain (loss) on Japanese yen-denominated debt		5		3			123		(11)
Research, development, and engineering expenses	[6],[7]	(35)		(37)			(69)		(76)
Equity in (losses) earnings of affiliated companies	[8]	(1)		81			(1)		99
Amortization of intangibles		(33)		(28)			(65)		(54)
Interest expense, net		(67)		(64)			(141)		(122)
Income tax benefit		91		55			1		129
Cumulative adjustment related to customer contract	[6],[9]								(105)
Severance charges	[7]	(1)		(58)			(1)		(135)
Asset impairment	[7]			(195)					(195)
Capacity realignment and other charges and credits	[7]	(1)		(84)			(1)		(232)
Gain on sale of business		40					54
Other corporate items		$ (127)		$ (61)			$ (221)		$ (57)

[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 (loss).

[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] 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.

[9] 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.