Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Unrealized gain on certain investments, tax	$ 1			$ 1
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax Effect [Abstract]
Unrealized loss arising during period, tax	(11)	9	(39)	(23)
Reclassification adjustment for losses included in net earnings, tax	(10)	(12)	(19)	(24)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax, Portion Attributable to Parent [Abstract]
Amortization of prior service cost included in net periodic pension cost, tax	15	8	31	15
Net actuarial gains arising during the period, tax		34	(1)	215
Amortization of actuarial losses included in net periodic pension cost, tax	(73)	(73)	(145)	(145)
Settlements and curtailments included in net income, tax		(1)		(7)
Pension and post retirement benefits related to our equity method investments, tax		$ 3	$ 1	$ (1)