Note 3 - Contracts With Customers 1 (Details Textual)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
VoC Platform [Member]
Revenue from Contract with Customer, Percent of Total Revenue	73.30%	62.70%	49.60%

The percent of total revenue from contracts with customers.

No definition available.

Name:	nrc_RevenueFromContractWithCustomerPercentOfTotalRevenue
Namespace Prefix:	nrc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration