v3.6.0.2
Income Taxes (Components of Net Deferred Tax Liability) (Details) - USD ($)
$ in Millions
Dec. 31, 2016
Dec. 31, 2015
Deferred Tax Assets:    
Net operating loss carryforwards $ 544 $ 551
Nondeductible accruals and other 3,789 3,704
Less: Valuation allowance 266 342
Total deferred tax assets, net of valuation allowance 4,067 4,014
Deferred Tax Liabilities:    
Total deferred tax liabilities 38,880 37,580
Net deferred tax liability 34,813 33,566
Differences Between Book and Tax Basis of Property and Equipment and Intangible Assets [Member]    
Deferred Tax Liabilities:    
Deferred tax liabilities, other 37,401 36,392
Differences Between Book and Tax Basis of Investments [Member]    
Deferred Tax Assets:    
Deferred tax asset, other 0 101
Deferred Tax Liabilities:    
Deferred tax liabilities, other 144 0
Differences Between Book and Tax Basis of Indexed Debt Securities [Member]    
Deferred Tax Liabilities:    
Deferred tax liabilities, other 375 457
Differences Between Book and Tax Basis of Foreign Subsidiaries [Member]    
Deferred Tax Liabilities:    
Deferred tax liabilities, other $ 960 $ 731