Note 16 - Reportable Segments - Reportable Segments (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Depreciation				$ 666	$ 680
Research, development and engineering expenses		$ 242	$ 430	464	691
Income tax (provision) benefit		67	22	293	10
Net income (loss) attributable to Corning Incorporated		449	(71)	1,048	(167)
Operating Segments [Member]
Net sales of reportable segments and All Other		3,504	2,588	6,767	5,117
Depreciation	[1]	332	293	659	589
Research, development and engineering expenses	[2]	200	181	387	390
Income tax (provision) benefit	[3]	(158)	(77)	(294)	(139)
Net income (loss) attributable to Corning Incorporated	[4]	595	288	1,108	524
Display Products [Member] | Operating Segments [Member]
Net sales of reportable segments and All Other		939	753	1,802	1,504
Depreciation	[1]	149	133	297	266
Research, development and engineering expenses	[2]	26	25	48	55
Income tax (provision) benefit	[3]	(64)	(41)	(120)	(81)
Net income (loss) attributable to Corning Incorporated	[4]	248	152	461	304
Optical Communications [Member] | Operating Segments [Member]
Net sales of reportable segments and All Other		1,075	887	2,012	1,678
Depreciation	[1]	58	62	116	124
Research, development and engineering expenses	[2]	52	52	103	107
Income tax (provision) benefit	[3]	(40)	(23)	(71)	(31)
Net income (loss) attributable to Corning Incorporated	[4]	148	81	259	110
Specialty Materials [Member] | Operating Segments [Member]
Net sales of reportable segments and All Other		483	417	934	769
Depreciation	[1]	42	38	83	80
Research, development and engineering expenses	[2]	49	33	94	74
Income tax (provision) benefit	[3]	(22)	(24)	(46)	(38)
Net income (loss) attributable to Corning Incorporated	[4]	81	90	172	141
Environmental Technologies [Member] | Operating Segments [Member]
Net sales of reportable segments and All Other		407	226	848	546
Depreciation	[1]	35	33	71	67
Research, development and engineering expenses	[2]	29	22	56	50
Income tax (provision) benefit	[3]	(21)	0	(41)	(9)
Net income (loss) attributable to Corning Incorporated	[4]	81	0	155	35
Life Science Products [Member] | Operating Segments [Member]
Net sales of reportable segments and All Other		312	243	612	501
Depreciation	[1]	14	13	26	25
Research, development and engineering expenses	[2]	8	6	16	13
Income tax (provision) benefit	[3]	(14)	(8)	(27)	(18)
Net income (loss) attributable to Corning Incorporated	[4]	52	31	100	69
Other Segments [Member] | Operating Segments [Member]
Net sales of reportable segments and All Other		288	62	559	119
Depreciation	[1]	34	14	66	27
Research, development and engineering expenses	[2]	36	43	70	91
Income tax (provision) benefit	[3]	3	19	11	38
Net income (loss) attributable to Corning Incorporated	[4]	$ (15)	$ (66)	$ (39)	$ (135)

[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 (loss).