Employment Benefit Plans (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Number of months for highest consecutive compensation	60 months
Total number of years of salaried employees to qualify for pension plans	10 years
Number of funded plans	2
Transition period	10 years
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Curtailment gain as a result of plan amendments		$ 120
Curtailment gain	$ 0	(117)
Amortization of prior service credits	0	(3)
Service cost	5	10
Interest cost	18	22
Expected return on plan assets	(42)	(39)
Amortization of net gain	0	(1)
Net cost recognized	$ (19)	$ (128)