Consolidated Statements Of Comprehensive Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Interest income:
Interest income	$ 293	$ 318	$ 589	$ 613
Interest expense	112	101	210	200
Net interest income	181	217	379	413
Other gain (loss), net:
Gain (loss) on sale of investment securities, net	15	55	(69)	53
Unrealized gain on investment securities measured at fair value through net income, net	9	0	25	11
Loss on derivative instruments and other securities, net	(169)	(367)	(209)	(1,311)
Management fee income	4	0	7	0
Total other loss, net:	(141)	(312)	(246)	(1,247)
Expenses:
Management fee expense	0	25	0	52
Compensation and benefits	10	0	20	0
Other operating expenses	6	15	13	21
Total operating expenses	16	40	33	73
Net income (loss)	24	(135)	100	(907)
Dividend on preferred stock	7	7	14	14
Net income (loss) available (attributable) to common stockholders	17	(142)	86	(921)
Other comprehensive income (loss):
Unrealized gain on available-for-sale securities, net	(121)	(370)	(167)	(1,135)
Unrealized gain on derivative instruments, net	0	12	0	31
Other comprehensive income	121	382	167	1,166
Comprehensive income	145	247	267	259
Comprehensive income available to common stockholders	$ 138	$ 240	$ 253	$ 245
Weighted average number of common shares outstanding - basic	346.4	331.0	338.8	332.7
Weighted average number of common shares outstanding - diluted	346.5	331.0	338.9	332.7
Net income (loss) per common share - basic and diluted	$ 0.05	$ (0.43)	$ 0.25	$ (2.77)
Dividends declared per common share	$ 0.54	$ 0.60	$ 1.08	$ 1.20