Consolidated Statements Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Cash Flows [Abstract]
Interest Paid	$ 332	$ 215	$ 217
Operating activities:
Net income (loss)	623	215	(233)
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of premiums and discounts on mortgage-backed securities, net	400	408	472
Amortization of accumulated other comprehensive loss on interest rate swaps de-designated as qualifying hedges	39	101	156
Amortization of intangible assets	2	0	0
Stock based compensation	1	0	0
(Gain) loss on sale of mortgage-backed securities, net	(109)	23	(51)
Unrealized loss on investment securities measured at fair value through net income, net	6	5	32
Loss on derivative instruments and other securities, net	310	754	1,211
(Increase) decrease in other assets	34	(83)	55
Increase (decrease) in accounts payable and other accrued liabilities	46	5	(20)
Net cash provided by operating activities	1,352	1,428	1,622
Investing activities:
Purchases of mortgage-backed securities	(20,836)	(32,770)	(26,349)
Payments To Acquire Non- Agency Mortgage Backed Securities	(34)	(116)	0
Proceeds from sale of mortgage-backed securities	18,030	27,794	30,587
Principal collections on mortgage-backed securities	8,137	7,922	7,358
Purchases of credit risk transfer securities	(195)	0	0
Purchases of U.S. Treasury securities	(4,483)	(49,724)	(51,511)
Proceeds from sale of U.S. Treasury securities	10,393	48,354	56,068
Net proceeds from (payments on) reverse repurchase agreements	(6,003)	3,505	(3,337)
Net proceeds from (payments on) other derivative instruments	(1,399)	(300)	313
Purchases of REIT equity securities	0	(11)	(234)
Proceeds from sale of REIT equity securities	39	35	416
Purchase of AGNC Mortgage Management, LLC, net of cash acquired	(555)	0	0
(Increase) decrease in restricted cash and cash equivalents	1,244	(568)	(612)
Other investing cash flows, net	107	(28)	(350)
Net cash provided by investing activities	4,445	4,093	12,349
Financing activities:
Proceeds from repurchase arrangements	217,501	380,580	291,736
Payments on repurchase agreements	(221,434)	(389,122)	(304,973)
Proceeds from Federal Home Loan Bank advances	2,098	12,957	0
Payments on Federal Home Loan Bank advances	(2,814)	(9,204)	0
Payments on debt of consolidated variable interest entities	(135)	(155)	(158)
Proceeds from Issuance of Preferred Stock and Preference Stock	0	0	169
Payments for common stock repurchases	(116)	(285)	(74)
Cash dividends paid	(799)	(902)	(1,094)
Net cash used in financing activities	(5,699)	(6,131)	(14,394)
Net change in cash and cash equivalents	98	(610)	(423)
Cash and cash equivalents at beginning of period	1,110	1,720	2,143
Cash and cash equivalents at end of period	1,208	1,110	1,720
Income Taxes Paid	$ 0	$ 1	$ 3