Repurchase Agreements - Narrative (Details)	Sep. 30, 2024 counterparty
Disclosure of Repurchase Agreements [Abstract]
Number of counterparties	28

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