Guarantor Financial Statement Information - Narrative (Details) $ in Millions	Dec. 31, 2019 USD ($) subsidiary	Dec. 31, 2018 USD ($)
Ownership percentage	100.00%
Number of direct wholly owned subsidiaries | subsidiary	3
Unsecured Senior Notes
Unsecured senior notes principal amount	$ 2,398	$ 2,498
$600 face value, 6.500% interest rate payable semi-annually, due July 2021 | Unsecured Senior Notes
Interest rate	6.50%
Unsecured senior notes principal amount	$ 492	592
$300 face value, 6.500% interest rate payable semi-annually, due June 2022 | Unsecured Senior Notes
Interest rate	6.50%
Unsecured senior notes principal amount	$ 206	$ 206