Investments (Results From Operations) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Net sales			$ 11,303	$ 11,503	$ 11,290
Gross profit			3,531	4,035	4,461
Net income			523	979	1,090
Corning’s equity in earnings of affiliated companies			(25)	17	390
Dividends received from affiliated companies			1	106	241
Current assets			8,004	7,463
Noncontrolling interests			191	90
Inventory write-down				105
Affiliated Companies [Member]
Schedule of Equity Method Investments [Line Items]
Net sales			1,201	1,508	1,759
Gross profit			136	79	424
Net of tax			(48)	(102)	835
Net income			(15)	70	798
Corning’s equity in earnings of affiliated companies			(25)	17	390
Intercompany sales within HSG			253	277	184
Corning purchases from affiliated companies			8	12	11
Corning transfers of assets, at cost, to affiliated companies			9	8	2
Dividends received from affiliated companies			1	106	241
Current assets			534	1,566
Noncurrent assets			466	943
Short-term borrowings, including current portion of long-term debt			2	4
Other current liabilities			164	632
Long-term debt			60	68
Other long-term liabilities			11	1,522
Noncontrolling interests				42
Balances due from affiliated companies			36	42
Balances due to affiliated companies			1	4
HSG [Member]
Schedule of Equity Method Investments [Line Items]
Net sales			423	779	1,158
Gross profit			87	9	367
Net of tax			11	(117)	814
Net income			44	54	776
Corning’s equity in earnings of affiliated companies			22	27	388
Intercompany sales within HSG			55	112	206
Dividends received from affiliated companies				100	$ 241
Current assets			853	1,011
Noncurrent assets			725	420
Short-term borrowings, including current portion of long-term debt			178	3
Other current liabilities			337	412
Long-term debt			6	8
Other long-term liabilities			1,499	1,507
Noncontrolling interests			9	42
Intercompany receivables and payables within HSG (included in current assets and other current liabilities)			$ 8	15
Pre-tax gain on settlements of long-term sales agreements	$ 200	$ 165
Inventory write-down		$ 44		$ 257
Gain on settlements of long-term sales agreements, net	19
Pre-existing contract disputes, loss on settlement	$ 81