Equity Compensation Plan - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended		6 Months Ended	12 Months Ended			58 Months Ended
	May 24, 2007	Oct. 31, 2006	Oct. 31, 2005	Jun. 30, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2011	Oct. 14, 2016	Aug. 05, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock (in shares)				0
Grant of restricted stock					146,552
Paid or accrued compensation related to dividend equivalent right issued					$ 406	$ 376	$ 323
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock (in shares)					154,552
Restricted Stock Units (RSUs) | Independent Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock (in shares)					8,000
DER | Independent Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Grant of restricted stock					8,000
Performance-Based Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock (in shares)					146,552
Restricted shares, vesting term					3 years
Closing price of common stock on grant date					$ 4.96
Unrecognized stock compensation expense					$ 226
Performance-Based Restricted Stock Units | Return to Capital Exceeds 10%
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted shares, vesting term					10 years
Performance-Based Restricted Stock Units | Involuntary Termination
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted shares, vesting term					3 years
Performance-Based Restricted Stock Units | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of total return to stockholders					10.00%
Anworth Mortgage Asset Corporation 2014 Equity Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum authorized shares of common stock under grant of stock options and other stock-based awards										2,000,000
Termination date of restricted stock					Jan. 03, 2017
Anworth Mortgage Asset Corporation 2004 Equity Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum authorized shares of common stock under grant of stock options and other stock-based awards					3,500,000
Grant of restricted stock		197,362	200,780
Restricted shares, vesting term		3 years			10 years
Stock price on grant date		$ 9.12	$ 7.72
Percentage of restricted stock vests per year			10.00%
Age at which grantee has to reach for stock to vest immediately			65 years
Terms of stock vesting					The restricted stock vests 10% per year on each anniversary date for a ten-year period and shall also vest immediately upon the death of the grantee or upon the grantee reaching age 65. Each grantee shall have the right to sell 40% of the restricted stock any time after such shares have vested.
Percentage of restricted stock that each grantee have right to sell anytime after such shares have vested		40.00%	40.00%
Percentage of restricted stock that may not be sold until after termination of employment		60.00%	60.00%
Vesting range of restricted stock					We amortize the restricted stock over the vesting period, which is the lesser of ten years or the remaining number of years to age 65.
Effective date for grant of restricted stock		Oct. 18, 2006
Compensation expense related to restricted stock and restricted stock units grants					$ 337	97	97
Anworth Mortgage Asset Corporation 2004 Equity Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Annually compounded rate of return on common stock, including dividends, effective date of the grant to each of the next three anniversary dates		12.00%
Anworth Mortgage Asset Corporation 2007 Dividend Equivalent Rights Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend equivalent right issued, term								5 years
Dividend equivalent right issued					690,792
Dividend equivalent rights, granted									144,982
Dividend equivalent rights new grant									18,604
Dividend equivalent rights outstanding					690,792
Paid or accrued compensation related to dividend equivalent right issued					$ 406	$ 376	$ 323
Dividend equivalent rights expiration date					Dec. 31, 2016
Anworth Mortgage Asset Corporation 2007 Dividend Equivalent Rights Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend equivalent right issued, term	10 years