CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net interest income
Interest income	$ 763,378	$ 555,026
Interest expense	75,973	503,473
Net interest income	687,405	51,553
Realized and unrealized gains (losses)
Net interest component of interest rate swaps	(79,747)	(13,980)
Realized gains (losses) on termination or maturity of interest rate swaps	0	(397,561)
Unrealized gains (losses) on interest rate swaps	772,262	(2,827,723)
Subtotal	692,515	(3,239,264)
Net gains (losses) on disposal of investments and other	(65,786)	206,583
Net gains (losses) on other derivatives and financial instruments	476,868	206,426
Net unrealized gains (losses) on instruments measured at fair value through earnings	104,191	(730,160)
Loan loss (provision) reversal	139,620	(99,326)
Business divestiture-related gains (losses)	(249,563)	0
Subtotal	405,330	(416,477)
Total realized and unrealized gains (losses)	1,097,845	(3,655,741)
Other income (loss)	15,258	14,926
General and administrative expenses
Compensation and management fee	31,518	40,825
Other general and administrative expenses	18,177	36,804
Total general and administrative expenses	49,695	77,629
Income (loss) before income taxes	1,750,813	(3,666,891)
Income taxes	(321)	(26,702)
Net income (loss)	1,751,134	(3,640,189)
Net income (loss) attributable to noncontrolling interests	321	66
Net income (loss) attributable to Annaly	1,750,813	(3,640,255)
Dividends on preferred stock	26,883	35,509
Net income (loss) available (related) to common stockholders	$ 1,723,930	$ (3,675,764)
Net income (loss) per share available (related) to common stockholders
Basic (in dollars per share)	$ 1.23	$ (2.57)
Diluted (in dollars per share)	$ 1.23	$ (2.57)
Weighted average number of common shares outstanding
Basic (in shares)	1,399,210,925	1,430,994,319
Diluted (in shares)	1,400,000,727	1,430,994,319
Other comprehensive income (loss)
Net income (loss)	$ 1,751,134	$ (3,640,189)
Unrealized gains (losses) on available-for-sale securities	(1,428,927)	1,374,796
Reclassification adjustment for net (gains) losses included in net income (loss)	56,823	(391,616)
Other comprehensive income (loss)	(1,372,104)	983,180
Comprehensive income (loss)	379,030	(2,657,009)
Comprehensive income (loss) attributable to noncontrolling interests	321	66
Comprehensive income (loss) attributable to Annaly	378,709	(2,657,075)
Comprehensive income (loss) attributable to common stockholders	$ 351,826	$ (2,692,584)