Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2020	Aug. 04, 2020
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2020
Document Transition Report	false
Entity File Number	001-13709
Entity Registrant Name	ANWORTH MORTGAGE ASSET CORP
Entity Incorporation, State or Country Code	MD
Entity Address, Address Line One	1299 Ocean Avenue, 2nd Floor
Entity Address, City or Town	Santa Monica
Entity Address, State or Province	CA
Entity Tax Identification Number	52-2059785
Entity Address, Postal Zip Code	90401
City Area Code	310
Local Phone Number	255-4493
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		99,130,931
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Entity Central Index Key	0001047884
Amendment Flag	false
Common Stock
Title of 12(b) Security	Common Stock, $0.01 Par Value
Trading Symbol	ANH
Security Exchange Name	NYSE
Series A Preferred Stock
Title of 12(b) Security	Series A Cumulative Preferred Stock, $0.01 Par Value
Trading Symbol	ANHPRA
Security Exchange Name	NYSE
Series B Preferred Stock
Title of 12(b) Security	Series B Cumulative Convertible Preferred Stock, $0.01 Par Value
Trading Symbol	ANHPRB
Security Exchange Name	NYSE
Series C Preferred Stock
Title of 12(b) Security	Series C Cumulative Redeemable Preferred Stock, $0.01 Par Value
Trading Symbol	ANHPRC
Security Exchange Name	NYSE