Employee Benefit Plans - Fair Value of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	$ 148	$ 129	$ 107
Level 1
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	43	39
Level 2
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	96	85
Level 3
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	9	5	$ 4
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	58	62
Equity securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	41	35
Equity securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	17	27
Global return fund
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	32	19
Global return fund | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	32	19
Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	25	13
Corporate bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	25	13
Government bonds
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	5	12
Government bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	5	12
Real estate
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	9	5
Real estate | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	0
Real estate | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	9	5
LDI (Liability Driven Investment)
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	17	14
LDI (Liability Driven Investment) | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	17	14
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	2	4
Cash and cash equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	$ 2	$ 4