Accumulated Other Comprehensive Loss (Details 2) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Reclassifications out of accumulated other comprehensive income loss by component
INCOME BEFORE INCOME TAX EXPENSE	$ 317	$ 234	$ 697	$ 557
Income tax expense	(121)	(91)	(265)	(222)
Net income	196	143	432	335
Amount reclassified from accumulated other comprehensive loss
Reclassifications out of accumulated other comprehensive income loss by component
Net actuarial loss	(45)	(42)	(87)	(80)
Prior service cost	(3)	(7)	(6)	(13)
INCOME BEFORE INCOME TAX EXPENSE	(48)	(49)	(93)	(93)
Income tax expense	18	18	35	35
Net income	$ (30)	$ (31)	$ (58)	$ (58)