Employee Benefit Plans - Additional Information (Details) - Supplemental Employee Retirement Plans, Defined Benefit [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ 2	$ 2	$ 5	$ 5
Accrued benefits liabilities	77		$ 77		$ 72
Defined benefit plans and other post-retirement plans, weighted-average assumptions to determine net periodic cost, discount rate			3.10%	4.20%
Defined benefit plans and other post-retirement plans, weighted-average assumptions to determine net periodic cost, rate of compensation increase			3.00%	3.00%
Assets in a rabbi trust generally designated to pay benefits of the SERP	$ 87		$ 87		$ 84