Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) $ in Thousands	6 Months Ended
Jun. 30, 2026 USD ($)
Statement of Comprehensive Income [Abstract]
Reclassification adjustment for amounts realized in income, Income tax expense associated with gains	$ 57,000

Other comprehensive income (loss), reclassification adjustment from aoci for sale of securities, income tax expense (benefit) before tax.

No definition available.

Name:	nara_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesIncomeTaxExpenseBenefitBeforeTax
Namespace Prefix:	nara_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration