XML 87 R67.htm IDEA: XBRL DOCUMENT v3.10.0.1
Benefit Plans - Postretirement Health Care Costs (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 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 $ 16 $ 16
Postretirement Benefit Plans        
Defined Benefit Plan Disclosure [Line Items]        
Service cost 1 2 3 4
Interest cost 3 3 7 7
Net loss from experience differences 3 4 7 7
Prior service credit [1] (9) (10) (19) (20)
Net periodic benefit costs $ (2) $ (1) $ (2) $ (2)
[1] $8 million for the three months ended June 30, 2018 and June 30, 2017 and $16 million for the six months ended June 30, 2018 and June 30, 2017 related to a change in the eligibility requirement and a change in benefits to Medicare-eligible participants.