Repurchase Agreements - Narrative (Details) $ in Thousands	Sep. 30, 2023 USD ($) counterparty	Dec. 31, 2022 USD ($)
Disclosure of Repurchase Agreements [Abstract]
Number of counterparties \| counterparty	27
Due to counterparties \| $	$ 152,955	$ 4,159

Number of lending counterparties with whom the Company has amounts outstanding as of reporting period.

No definition available.

Name:	dx_NumberOfCounterpartiesBorrowingsOutstanding
Namespace Prefix:	dx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant