XML 87 R67.htm IDEA: XBRL DOCUMENT v3.10.0.1
Long-Term Debt (Narrative) (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2016
Dec. 31, 2017
Debt Instrument [Line Items]      
Interest Payable $ 207   $ 219
Senior Notes [Member]      
Debt Instrument [Line Items]      
Extinguishment of debt   $ 933  
Senior Notes [Member]      
Debt Instrument [Line Items]      
Repayments of debt $ 864    
Senior Notes [Member] | Change Of Control And Loss Of Investment Grade Rating [Member]      
Debt Instrument [Line Items]      
Required purchase price as percentage of aggregate principal amount 101.00%    
Reported Value Measurement [Member]      
Debt Instrument [Line Items]      
Fair value of long term debt $ 13,000   13,900
Level 2 [Member] | Estimate of Fair Value Measurement [Member]      
Debt Instrument [Line Items]      
Fair value of long term debt $ 12,500   $ 15,300