SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF PARENT - STATEMENT OF COMPREHENSIVE INCOME (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Condensed Statement of Income Captions [Line Items]
Net income	$ 964	$ 334	$ (530)	$ 358	$ (451)	$ 102	$ 248	$ 452	$ 1,126	$ 351	[1]	$ 1,519	[1]
Total other comprehensive (loss) income									(133)	142		52
Pretax amount [Member]
Condensed Statement of Income Captions [Line Items]
Net income									1,146	1,533		1,760
Foreign currency translation adjustments									(144)	107		42
Financial instruments									64	2		(6)
Pension and other postretirement benefits									(38)	20		(13)
Total other comprehensive (loss) income									(118)	129		23
Total comprehensive income, after preferred dividends of subsidiaries									1,027	1,661		1,782
Income tax benefit [Member]
Condensed Statement of Income Captions [Line Items]
Net income									(96)	(1,276)		(389)
Foreign currency translation adjustments									0	0		0
Financial instruments									(21)	1		11
Pension and other postretirement benefits									4	(8)		4
Total other comprehensive (loss) income									(17)	(7)		15
Total comprehensive income, after preferred dividends of subsidiaries									(113)	(1,283)		(374)
Net-of-tax amount [Member]
Condensed Statement of Income Captions [Line Items]
Net income									1,050	257		1,371
Foreign currency translation adjustments									(144)	107		42
Financial instruments									43	3		5
Pension and other postretirement benefits									(34)	12		(9)
Total other comprehensive (loss) income									(135)	122		38
Total comprehensive income, after preferred dividends of subsidiaries									914	378		1,408
Parent Company [Member]
Condensed Statement of Income Captions [Line Items]
Net income									1,049	256	[1]	1,370	[1]
Parent Company [Member] | Pretax amount [Member]
Condensed Statement of Income Captions [Line Items]
Net income									895	223		1,189
Foreign currency translation adjustments									(144)	107		42
Financial instruments									64	2		(6)
Pension and other postretirement benefits									(38)	20		(13)
Total other comprehensive (loss) income									(118)	129		23
Total comprehensive income, after preferred dividends of subsidiaries									777	352		1,212
Parent Company [Member] | Income tax benefit [Member]
Condensed Statement of Income Captions [Line Items]
Net income									154	33		181
Foreign currency translation adjustments									0	0		0
Financial instruments									(21)	1		11
Pension and other postretirement benefits									4	(8)		4
Total other comprehensive (loss) income									(17)	(7)		15
Total comprehensive income, after preferred dividends of subsidiaries									137	26		196
Parent Company [Member] | Net-of-tax amount [Member]
Condensed Statement of Income Captions [Line Items]
Net income									1,049	256		1,370
Foreign currency translation adjustments									(144)	107		42
Financial instruments									43	3		5
Pension and other postretirement benefits									(34)	12		(9)
Total other comprehensive (loss) income									(135)	122		38
Total comprehensive income, after preferred dividends of subsidiaries									$ 914	$ 378		$ 1,408

[1] As adjusted for the retrospective adoption of ASU 2017-07, which we discuss in Note 2, and a reclassification to conform to current year presentation, which we discuss in Note 1.