Segment Information (Details 3) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total reportable segment income	$ 631	$ 688
Depreciation and amortization	(880)	(976)
Other operating expenses	(3,578)	(3,713)
Interest expense and other (expense) income, net	(324)	(308)
INCOME BEFORE INCOME TAX EXPENSE	307	380
Income tax expense	(144)	(144)
Net income	163	236
Operating segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total reportable segment income	1,838	2,001
Segment reconciling items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Non-reportable segment revenues	153	162
Other operating revenues	288	308
Depreciation and amortization	(880)	(976)
Other operating expenses	(768)	(807)
Interest expense and other (expense) income, net	(324)	(308)
INCOME BEFORE INCOME TAX EXPENSE	307	380
Income tax expense	$ (144)	$ (144)