XML 68 R55.htm IDEA: XBRL DOCUMENT v3.19.2
Fair Value Measurements - Investment Maturities (Details) - Fair Value - USD ($)
$ in Millions
Jun. 30, 2019
Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Less than 1 year $ 878 $ 253
1 - 5 years 8 14
5 - 10 years 27 26
Greater than 10 years 51 48
Total investments at fair value $ 964 $ 341