Note 4 - Regulatory Matters (Details Textual)	Jan. 01, 2019	Dec. 31, 2015
Capital Conservation Buffer		0.00%
Scenario, Forecast [Member]
Capital Conservation Buffer	2.50%

A buffer of capital above the regulatory minimum designed to avoid breaches of minimum capital requirements.

No definition available.

Name:	nwbb_CapitalConservationBuffer
Namespace Prefix:	nwbb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant