Financial Instruments and Fair Value Measures - Summary of Financial Assets and Liabilities Not Carried at Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Liabilities not subject to compromise	$ 3,028	$ 3,035
Carrying Value | Terms Loans A and B
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Liabilities not subject to compromise	1,055
Carrying Value | Debtor In Possession Financing
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Liabilities not subject to compromise	100
Carrying Value | 5.125% Senior Notes Due 2026
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Liabilities not subject to compromise	412
Fair Value | Terms Loans A and B | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Liabilities not subject to compromise	1,073
Fair Value | Debtor In Possession Financing | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Liabilities not subject to compromise	100
Fair Value | 5.125% Senior Notes Due 2026 | Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Liabilities not subject to compromise	$ 440