Note 16 - Reportable Segments - Reportable Segments (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Depreciation		$ 330	$ 356
Research, development and engineering expenses		222	261
Income tax (provision) benefit		226	(12)
Net income (loss) attributable to Corning Incorporated		599	(96)
Operating Segments [Member]
Net sales of reportable segments and All Other		3,263	2,529
Depreciation	[1]	327	296
Research, development and engineering expenses	[2]	187	209
Income tax (provision) benefit	[3]	(136)	(62)
Net income (loss) attributable to Corning Incorporated	[4]	513	236
Display Products [Member] | Operating Segments [Member]
Net sales of reportable segments and All Other		863	751
Depreciation	[1]	148	133
Research, development and engineering expenses	[2]	22	30
Income tax (provision) benefit	[3]	(56)	(40)
Net income (loss) attributable to Corning Incorporated	[4]	213	152
Optical Communications [Member] | Operating Segments [Member]
Net sales of reportable segments and All Other		937	791
Depreciation	[1]	58	62
Research, development and engineering expenses	[2]	51	55
Income tax (provision) benefit	[3]	(31)	(8)
Net income (loss) attributable to Corning Incorporated	[4]	111	29
Specialty Materials [Member] | Operating Segments [Member]
Net sales of reportable segments and All Other		451	352
Depreciation	[1]	41	42
Research, development and engineering expenses	[2]	45	41
Income tax (provision) benefit	[3]	(24)	(14)
Net income (loss) attributable to Corning Incorporated	[4]	91	51
Environmental Technologies [Member] | Operating Segments [Member]
Net sales of reportable segments and All Other		441	320
Depreciation	[1]	36	34
Research, development and engineering expenses	[2]	27	28
Income tax (provision) benefit	[3]	(20)	(9)
Net income (loss) attributable to Corning Incorporated	[4]	74	35
Life Science Products [Member] | Operating Segments [Member]
Net sales of reportable segments and All Other		300	258
Depreciation	[1]	12	12
Research, development and engineering expenses	[2]	8	7
Income tax (provision) benefit	[3]	(13)	(10)
Net income (loss) attributable to Corning Incorporated	[4]	48	38
Other Segments [Member] | Operating Segments [Member]
Net sales of reportable segments and All Other		271	57
Depreciation	[1]	32	13
Research, development and engineering expenses	[2]	34	48
Income tax (provision) benefit	[3]	8	19
Net income (loss) attributable to Corning Incorporated	[4]	$ (24)	$ (69)

[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).