XML 53 R41.htm IDEA: XBRL DOCUMENT v3.21.2
Fair Value Disclosures - Narrative (Details) - USD ($)
$ in Millions
Jun. 30, 2021
Dec. 31, 2020
Debt Instrument [Line Items]    
Carrying value $ 11,811 $ 12,903
Level 2    
Debt Instrument [Line Items]    
Estimated fair value of long-term debt portfolio $ 12,160 $ 13,611