Employee Benefit Plans - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Automatic enrollment feature pre-tax	6.00%
Maximum employer contribution	50.00%
Maximum employee contributions percentage to receive 50% matching	6.00%
Employer match, percent	3.00%
Contributions vested with the employees	2 years
Contributions to plans	$ 11	$ 14	$ 13
Target bonus multiplier	1, 1.5 or 2
Severance expense	$ 5
Director
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Common stock shares issued to non-employee directors	557
Director | 2011 Plan
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Common stock reserved for issuance to non-employee directors	100,000
Maximum
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
No of installments for payments upon termination	Payments upon termination will be made in either one lump sum or up to five annual installments, as elected by the eligible director at the time of the deferral election.
Period of continued payment of base salary in event of termination by company without cause more than 3 months prior to or 12 months following change in control	18 months
Period of continued coverage of health insurance premium in event of termination by company without cause more than 3 months prior to or 12 months following change in control	18 months
Period of lump sum salary payment in event of termination by company without cause or by participant for good reason within 3 months prior to or 12 months following change in control	24 months
Period of lump sum insurance premium payment in event of termination by company without cause or by participant for good reason within 3 months prior to or 12 months following change in control	24 months
Minimum
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Period of continued payment of base salary in event of termination by company without cause more than 3 months prior to or 12 months following change in control	6 months
Period of continued coverage of health insurance premium in event of termination by company without cause more than 3 months prior to or 12 months following change in control	6 months
Period of lump sum salary payment in event of termination by company without cause or by participant for good reason within 3 months prior to or 12 months following change in control	12 months
Period of lump sum insurance premium payment in event of termination by company without cause or by participant for good reason within 3 months prior to or 12 months following change in control	12 months
Pre-tax basis
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Maximum annual employee contribution, percent	50.00%
After-tax basis
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Maximum annual employee contribution, percent	10.00%