Investment Securities Available For Sale, at Fair Value - Schedule of Weighted Average Lives of Investment Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
0 to 5 years	$ 2,795,776	$ 283,554
Over 5 to 10 years	261,736	1,727,269
10+ years	327,758	2,994
Total	$ 3,385,270	$ 2,013,817

Debt Securities, Trading, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Fair Value

No definition available.

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Namespace Prefix:	nymt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant