XML 82 R69.htm IDEA: XBRL DOCUMENT v3.10.0.1
Benefit Plans - Postretirement Health Care Costs (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]        
Gain related to a change in the eligibility requirement and a change in benefits to Medicare-eligible participants $ 8 $ 8 $ 24 $ 24
Postretirement Benefit Plans        
Defined Benefit Plan Disclosure [Line Items]        
Service cost 1 1 4 5
Interest cost 4 4 11 11
Net loss from experience differences 4 4 11 11
Prior service credit [1] (10) (10) (29) (30)
Net periodic benefit costs $ (1) $ (1) $ (3) $ (3)
[1] $8 million for the three months ended September 30, 2018 and September 30, 2017 and $24 million for the nine months ended September 30, 2018 and September 30, 2017 related to a change in the eligibility requirement and a change in benefits to Medicare-eligible participants.