v3.19.2
Cash, Cash Equivalents and Restricted Cash - Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($)
$ in Millions
Jun. 30, 2019
Dec. 31, 2018
Jun. 30, 2018
Dec. 31, 2017
Restricted Cash And Cash Equivalents Items [Line Items]        
Cash and cash equivalents $ 3,920 $ 6,302    
Restricted cash included in other assets $ 17 $ 17    
Restricted Cash, Asset, Statement of Financial Position [Extensible List] us-gaap:OtherAssetsMember us-gaap:OtherAssetsMember    
Total cash, cash equivalents and restricted cash $ 4,040 $ 6,505 $ 6,741 $ 7,096
Consolidated Variable Interest Entities [Member]        
Restricted Cash And Cash Equivalents Items [Line Items]        
Cash and cash equivalents $ 103 $ 186