Annual report pursuant to Section 13 and 15(d)

Income Taxes - Changes in Gross Amounts of Unrecognized Tax Benefits (Details)

v3.10.0.1
Income Taxes - Changes in Gross Amounts of Unrecognized Tax Benefits (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]    
Balance at beginning of year $ 62 $ 103
Additions based on tax positions related to current year 0 0
Additions for tax positions of prior years 0 0
Reductions for tax positions of prior years (1) (1)
Settlements 0 0
U.S. tax reform rate change 0 (40)
Balance at end of year $ 61 $ 62