Income Taxes (Components of Income Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Federal	$ 3,210	$ 2,392	$ 3,183
State	570	174	581
Foreign	221	142	200
Current income tax expense (benefit)	4,001	2,708	3,964
Federal	890	1,000	(76)
State	66	173	108
Foreign deferred income tax expense	2	(8)	(16)
Deferred income tax expense (benefit)	958	1,165	16
Income tax expense	4,959	3,873	3,980
NBCUniversal Media LLC [Member]
Foreign	81	33	77
Foreign deferred income tax expense	2	(8)	(16)
Deferred income tax expense (benefit)	(11)	(12)	(10)
Withholding tax expense	139	108	123
U.S. domestic tax expense	5	10	22
Income tax expense	$ 227	$ 143	$ 206