Income Taxes (Significant Components of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Stock-based compensation expense	$ 574	$ 534
Accrued employee benefits	939	832
Accruals and reserves not currently deductible	500	245
Tax credits	631	503
Basis difference in investment of Arris	1,327	1,357
Prepaid cost sharing	4,409	3,468
Other	926	931
Total deferred tax assets	9,306	7,870
Valuation allowance	(2,076)	(1,732)
Total deferred tax assets net of valuation allowance	7,230	6,138
Deferred tax liabilities:
Depreciation and amortization	(877)	(1,126)
Identified intangibles	(844)	(787)
Renewable energy investments	(788)	(529)
Foreign earnings	(4,409)	(3,468)
Other	(155)	(166)
Total deferred tax liabilities	(7,073)	(6,076)
Net deferred tax assets	$ 157	$ 62