Pension and Other Postretirement Benefits - Funded Status (Details) - United States [Member] - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Change in plan assets [Roll Forward]
Expected plan contributions for the remaining fiscal year
Pension Benefits [Member]
Change in benefit obligation [Abstract]
Service cost	0	$ 0	1,000,000	$ 1,000,000
Interest cost	48,000,000	42,000,000	97,000,000	84,000,000
Pension Benefits [Member] | Qualified Plan [Member]
Change in plan assets [Roll Forward]
Contributions			0
Other Postretirement Benefits [Member]
Change in benefit obligation [Abstract]
Service cost	0	0	0	0
Interest cost	$ 2,000,000	$ 2,000,000	$ 4,000,000	$ 4,000,000