XML 83 R72.htm IDEA: XBRL DOCUMENT v3.8.0.1
Postretirement Benefit Plans - Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets (Detail) - Qualified Defined Benefit Pension Plans - USD ($)
$ in Millions
Dec. 31, 2017
Dec. 31, 2016
Plans where ABO was in excess of plan assets    
Projected benefit obligation $ 48,628 $ 44,946
Less: fair value of plan assets 32,925 31,091
Unfunded status of plans (15,703) (13,855)
Plans where ABO was less than plan assets    
Projected benefit obligation 58 118
Less: fair value of plan assets 170 326
Funded status of plans $ 112 $ 208