CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net interest income
Interest income		$ 919,299,000	$ 816,596,000	$ 2,713,083,000	$ 2,472,889,000
Interest expense		766,905,000	500,973,000	2,164,817,000	1,311,086,000
Net interest income		152,394,000	315,623,000	548,266,000	1,161,803,000
Realized and unrealized gains (losses)
Net interest component of interest rate swaps		88,466,000	51,349,000	306,154,000	34,664,000
Realized gains (losses) on termination or maturity of interest rate swaps		(682,602,000)	575,000	(1,438,349,000)	1,409,000
Unrealized gains (losses) on interest rate swaps		(326,309,000)	417,203,000	(1,992,884,000)	1,737,963,000
Subtotal		(920,445,000)	469,127,000	(3,125,079,000)	1,774,036,000
Net gains (losses) on disposal of investments		66,522,000	(324,294,000)	(65,727,000)	(376,943,000)
Net gains (losses) on other derivatives		(16,888,000)	94,827,000	(638,458,000)	81,871,000
Net unrealized gains (losses) on instruments measured at fair value through earnings		(1,091,000)	(39,944,000)	41,657,000	(139,913,000)
Loan loss provision		(3,504,000)	0	(9,207,000)	0
Subtotal		45,039,000	(269,411,000)	(671,735,000)	(434,985,000)
Total realized and unrealized gains (losses)		(875,406,000)	199,716,000	(3,796,814,000)	1,339,051,000
Other income (loss)		35,074,000	(10,643,000)	93,757,000	57,550,000
General and administrative expenses
Compensation and management fee		41,161,000	45,983,000	130,225,000	136,091,000
Other general and administrative expenses		24,977,000	80,526,000	98,058,000	116,709,000
Total general and administrative expenses		66,138,000	126,509,000	228,283,000	252,800,000
Income (loss) before income taxes		(754,076,000)	378,187,000	(3,383,074,000)	2,305,604,000
Income taxes		(6,907,000)	(7,242,000)	(10,241,000)	(3,416,000)
Net income (loss)		(747,169,000)	385,429,000	(3,372,833,000)	2,309,020,000
Net income (loss) attributable to noncontrolling interests		(110,000)	(149,000)	(294,000)	(277,000)
Net income (loss) attributable to Annaly		(747,059,000)	385,578,000	(3,372,539,000)	2,309,297,000
Dividends on preferred stock	[1]	36,151,000	31,675,000	101,067,000	96,818,000
Net income (loss) available (related) to common stockholders		$ (783,210,000)	$ 353,903,000	$ (3,473,606,000)	$ 2,212,479,000
Net income (loss) per share available (related) to common stockholders
Basic (in dollars per share)		$ (0.54)	$ 0.29	$ (2.42)	$ 1.88
Diluted (in dollars per share)		$ (0.54)	$ 0.29	$ (2.42)	$ 1.88
Weighted average number of common shares outstanding
Basic (in shares)		1,453,359,211	1,202,353,851	1,436,204,582	1,174,292,701
Diluted (in shares)		1,453,359,211	1,202,353,851	1,436,204,582	1,174,292,701
Net income (loss)		$ (747,169,000)	$ 385,429,000	$ (3,372,833,000)	$ 2,309,020,000
Other comprehensive income (loss)
Unrealized gains (losses) on available-for-sale securities		1,034,873,000	(719,609,000)	4,289,054,000	(3,104,218,000)
Reclassification adjustment for net (gains) losses included in net income (loss)		(86,061,000)	331,100,000	4,626,000	407,282,000
Other comprehensive income (loss)		948,812,000	(388,509,000)	4,293,680,000	(2,696,936,000)
Comprehensive income (loss)		201,643,000	(3,080,000)	920,847,000	(387,916,000)
Comprehensive income (loss) attributable to noncontrolling interests		(110,000)	(149,000)	(294,000)	(277,000)
Comprehensive income (loss) attributable to Annaly		201,753,000	(2,931,000)	921,141,000	(387,639,000)
Comprehensive income (loss) attributable to common stockholders		$ 165,602,000	$ (34,606,000)	$ 820,074,000	$ (484,457,000)

[1] ⁽¹⁾  The three months ended September 30, 2019 exclude cumulative and undeclared dividends of $0.3 million on the Company's Series I Preferred Stock as of June 30, 2019.