Pension - 401(k) Plans (Details) - USD ($) $ in Millions |
12 Months Ended | ||
---|---|---|---|
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
Pension and Other Postretirement Benefit Plans [Abstract] | |||
Expense for matching contributions in the 401K plan | $ 256 | $ 196 | $ 122 |