Securitized Mortgage Trusts - Change in Fair Value of Net Trust Assets (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Change in fair value of net trust assets, including trust REO losses
Change in fair value of net trust assets, excluding REO	$ (4,096)	$ (6,156)
Gains from REO	1,713	3,473
Change in fair value of net trust assets, including trust REO gains	$ (2,383)	$ (2,683)

This element represents change in fair value of trust assets including gain or loss on real estate owned due to increases or decreases in the fair value of investment securities-for-sale, securitized mortgage collateral and securitized mortgage borrowings during the reporting period.

No definition available.

Name:	imh_TrustAssetsNetChangeInFairValueIncludingRealEstateOwnedGainLoss
Namespace Prefix:	imh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration