XML 94 R80.htm IDEA: XBRL DOCUMENT v3.8.0.1
Derivative Instruments, Hedging Activities and Fair Value Measurements, Other Fair Value Measurements (Details) - USD ($)
$ in Millions
Mar. 31, 2018
Dec. 31, 2017
Carrying Value [Member]    
Financial Liabilities: [Abstract]    
Fixed Rate Debt Principal Amount Fair Value Disclosure $ 23,500 $ 21,480
Level 2 [Member] | Fair Value [Member]    
Financial Liabilities: [Abstract]    
Fixed Rate Debt Principal Amount Fair Value Disclosure $ 24,730 $ 23,470