Fair Value Measurements - Reconciliation of Level 3 defined benefit plan assets (Details) - Fair Value, Inputs, Level 3 [Member] $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of plan assets, January 1	$ 0
Purchase of insurance contract	106
Unrealized gains on assets still held at the reporting date	2
Level 3 reconciliation, translation adjustment	2
Fair value of plan assets, December 31	$ 110