SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF PARENT - STATEMENT OF COMPREHENSIVE INCOME (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Statement of Income Captions [Line Items]
Net income	$ 500	$ 909	$ 435	$ 518	$ 964	$ 334	$ (530)	$ 358	$ 2,362	$ 1,126	$ 351
Total other comprehensive (loss) income									(140)	(133)	142
Pretax amount [Member]
Condensed Statement of Income Captions [Line Items]
Net income									2,585	1,146	1,533
Foreign currency translation adjustments									(43)	(144)	107
Financial instruments									(161)
Financial instruments										64	2
Pension and other postretirement benefits									25	(38)	20
Total other comprehensive (loss) income									(179)	(118)	129
Total comprehensive income, after preferred dividends of subsidiaries									2,405	1,027	1,661
Income tax benefit [Member]
Condensed Statement of Income Captions [Line Items]
Net income									(387)	(96)	(1,276)
Foreign currency translation adjustments									0	0	0
Financial instruments									53
Financial instruments										(21)	1
Pension and other postretirement benefits									(7)	4	(8)
Total other comprehensive (loss) income									46	(17)	(7)
Total comprehensive income, after preferred dividends of subsidiaries									(341)	(113)	(1,283)
Net-of-tax amount [Member]
Condensed Statement of Income Captions [Line Items]
Net income									2,198	1,050	257
Foreign currency translation adjustments									(43)	(144)	107
Financial instruments									(108)
Financial instruments										43	3
Pension and other postretirement benefits									18	(34)	12
Total other comprehensive (loss) income									(133)	(135)	122
Total comprehensive income, after preferred dividends of subsidiaries									2,064	914	378
Parent Company [Member]
Condensed Statement of Income Captions [Line Items]
Net income									2,197	1,049	256
Parent Company [Member] | Pretax amount [Member]
Condensed Statement of Income Captions [Line Items]
Net income									2,034	895	223
Foreign currency translation adjustments									(43)	(144)	107
Financial instruments									(161)
Financial instruments										64	2
Pension and other postretirement benefits									25	(38)	20
Total other comprehensive (loss) income									(179)	(118)	129
Total comprehensive income, after preferred dividends of subsidiaries									1,855	777	352
Parent Company [Member] | Income tax benefit [Member]
Condensed Statement of Income Captions [Line Items]
Net income									163	154	33
Foreign currency translation adjustments									0	0	0
Financial instruments									53
Financial instruments										(21)	1
Pension and other postretirement benefits									(7)	4	(8)
Total other comprehensive (loss) income									46	(17)	(7)
Total comprehensive income, after preferred dividends of subsidiaries									209	137	26
Parent Company [Member] | Net-of-tax amount [Member]
Condensed Statement of Income Captions [Line Items]
Net income									2,197	1,049	256
Foreign currency translation adjustments									(43)	(144)	107
Financial instruments									(108)
Financial instruments										43	3
Pension and other postretirement benefits									18	(34)	12
Total other comprehensive (loss) income									(133)	(135)	122
Total comprehensive income, after preferred dividends of subsidiaries									$ 2,064	$ 914	$ 378