XML 81 R53.htm IDEA: XBRL DOCUMENT v3.19.1
Hedges and Derivative Financial Instruments - Narrative (Details) - USD ($)
3 Months Ended 12 Months Ended
Mar. 31, 2019
Dec. 31, 2018
Derivative [Line Items]    
Net hedge ineffectiveness gain (loss) $ 0 $ 0
Interest rate cash flow hedge loss to be reclassified during next 12 months 31,000,000  
Derivatives accounted for as hedges | Interest rate derivatives    
Derivative [Line Items]    
Notional amount $ 700,000,000 $ 0