Employee Benefit Plans - Additional Information (Details) - Supplemental Employee Retirement Plans, Defined Benefit [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ 2	$ 2	$ 4	$ 3
Accrued benefits liabilities	76		$ 76		$ 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	$ 85		$ 85		$ 84