Transactions with Affiliates (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Related Parties Details [Abstract]
Loans to affiliates and other	$ 10,659	$ 14,262	$ 15,303
Average interest rate on loans to affiliates and other	1.78%	1.81%	2.69%
Due from affiliates	$ 997	$ 615	$ 2,206
Short-term debt to affiliates	$ 4,559	$ 5,439	$ 4,334
Average interest rate on short-term debt to affiliates	0.49%	0.19%	0.15%
Maximum month-end level of borrowings during the year	$ 5,091	$ 5,439	$ 5,029
Due to affiliates	1,517	1,727	888
Maximum month-end level of loans to affiliates during the year	13,083	17,711	18,695
Interest income from affiliates and other	207	246	384
Interest expense to affiliates	24	10	6
Related Party Transaction [Line Items]
Other, net	14	(22)	(93)
Related Party [Member]
Related Party Transaction [Line Items]
Other, net	$ 1	$ 1	$ (3)