Accumulated Other Comprehensive Loss (Details 2) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Reclassifications out of accumulated other comprehensive income loss by component
INCOME BEFORE INCOME TAX EXPENSE	$ 380	$ 323
Income tax expense	(144)	(131)
Net income	236	192
Amount reclassified from accumulated other comprehensive loss
Reclassifications out of accumulated other comprehensive income loss by component
Net actuarial loss	(42)	(38)
Prior service cost	(3)	(6)
INCOME BEFORE INCOME TAX EXPENSE	(45)	(44)
Income tax expense	17	17
Net income	$ (28)	$ (27)