Investment Securities Available For Sale, at Fair Value - Weighted Average Lives for Available-for-Sale Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
0 to 5 years	$ 42,759	$ 39,655
Over 5 to 10 years	1,546,244	46,558
10+ years	13,212	13,346
Total	$ 1,602,215	$ 99,559

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

No definition available.

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