Employee Benefit Plans - Unobservable Input Reconciliation (Details) - Foreign Plan [Member] - USD ($) $ in Millions |
12 Months Ended | |
---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
|
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||
Fair value of plan assets as of January 1 | $ 978 | $ 1,009 |
Fair value of plan assets as of December 31 | 1,086 | 978 |
Significant Unobservable Inputs (Level 3) [Member] | ||
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||
Fair value of plan assets as of January 1 | 124 | 133 |
Realized and unrealized gains and losses, net | 7 | (8) |
Purchases, sales and settlements, net | 0 | 1 |
Transfers, net | 0 | (2) |
Fair value of plan assets as of December 31 | $ 131 | $ 124 |