Use of Estimates (Details)	6 Months Ended
Jun. 30, 2011
Use of Estimates [Abstract]
Uncertain tax positions are recognized threshold estimate (in hundredths)	50.00%

Name:

nbtb_UncertainTaxPositionsRecogntionMoreLikelyThanNot

Namespace Prefix:

nbtb

Data Type:

num:percentItemType

Balance Type:

na

Period Type:

duration