Consolidated Statements Of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statements of Comprehensive Income (Loss)
Net income (loss)	$ (1,229)	$ (27)	$ (1,301)	$ (105)
Unrealized gains (losses) on available-for-sale securities: [Abstract]
Unrealized gains (losses) arising during the period	44	101	4	224
Provision (benefit) for income taxes	6	36	0	79
Total	38	65	4	145
Reclassification adjustments for (gains) losses included in net income (loss)	(3)	13	(5)	8
Provision (benefit) for income taxes	1	5	0	3
Total	(4)	8	(5)	5
Available-for-sale securities with other-than-temporary impairments: [Abstract]
Other-than-temporary impairments and unrealized gains (losses) arising during the period	(47)	10	(34)	7
Provision (benefit) for income taxes	(5)	3	0	2
Total	(42)	7	(34)	5
Reclassification adjustments for (gains) losses included in net income (loss)	0	0	2	0
Provision (benefit) for income taxes	0	0	1	0
Total	0	0	1	0
Foreign currency translation: [Abstract]
Foreign currency translation gains (losses)	0	(41)	144	(55)
Provision (benefit) for income taxes	0	(14)	21	(19)
Total	0	(27)	123	(36)
Total other comprehensive income (loss)	(8)	53	89	119
Comprehensive income (loss)	$ (1,237)	$ 26	$ (1,212)	$ 14