Financial Instruments and Fair Value Measurements - Schedule of Aggregate Principal and Fair Value Amount of Outstanding 2025 Senior Notes and 2026 Senior Notes (Parenthetical) (Details) - Level 2 - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
2025 Senior Notes
Debt Instrument [Line Items]
Debt instrument, issuances costs	$ 8	$ 9
2026 Senior Notes
Debt Instrument [Line Items]
Debt instrument, issuances costs	$ 5