Other assets and liabilities - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Cash as collateral for certain derivatives	$ 9.6	$ 9.3
Cash posted as collateral by company	5.5	0.7
Cash pledged as collateral against derivatives related to variation margin	$ 4.1	$ 8.6

Represents the proceeds pledged to serve as collateral against certain derivatives during the period.

No definition available.

Name:	mitt_ProceedsPledgedToServeCollateralAgainstCertainDerivatives
Namespace Prefix:	mitt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration