Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Related Party Transaction [Line Items]
Cash distributions			$ 2,625	$ 1,750
Related Party Transaction Revenue with Affiliates	$ 32	$ 35	100	108
Related Party Transaction Expenditures from Transactions with Related Party	82	$ 73	243	210
Parent Company
Related Party Transaction [Line Items]
Cash distributions			2,625	1,750
Tax refunds from parent company			21	227
Tax payments to parent company			1,047	$ 451
Payable to Berkshire	188		188		$ 109
Earliest Tax Year [Member] | Parent Company
Related Party Transaction [Line Items]
Tax payable to parent related to prior year tax audits	$ 59		$ 59		$ 90