Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets (Detail) - Qualified defined benefit pension plans - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014
Plans where ABO was in excess of plan assets
Projected benefit obligation		$ 43,575	$ 45,741
Less: fair value of plan assets		31,768	34,328
Unfunded status of plans	[1]	(11,807)	(11,413)
Plans where ABO was less than plan assets
Projected benefit obligation		127	141
Less: fair value of plan assets		328	345
Funded status of plans	[2]	$ 201	$ 204

[1] Represent accrued pension liabilities, which are included on our Balance Sheets.

[2] Represent prepaid pension assets, which are included on our Balance Sheets in other noncurrent assets.