Regulatory Capital Requirements (Tables)

12 Months Ended

Dec. 31, 2012

Regulatory Capital Requirements [Abstract]

Schedule of compliance with regulatory compliance requirements under banking regulations

The Company and NBT Bank's actual capital amounts and ratios are presented as follows:

	Actual					Regulatory ratio requirements
(Dollars in thousands)	Amount		Ratio			Minimum capital adequacy			For classification as well capitalized
As of December 31, 2012
Total Capital (to risk weighted assets):
Company	$	560,745		12.25	%		8.00	%		10.00	%
NBT Bank		505,027		11.08	%		8.00	%		10.00	%
Tier I Capital (to risk weighted assets)
Company		503,359		11.00	%		4.00	%		6.00	%
NBT Bank		447,909		9.83	%		4.00	%		6.00	%
Tier I Capital (to average assets)
Company		503,359		8.54	%		4.00	%		5.00	%
NBT Bank		447,909		7.62	%		4.00	%		5.00	%
As of December 31, 2011
Total Capital (to risk weighted assets):
Company	$	528,674		12.81	%		8.00	%		10.00	%
NBT Bank		506,246		12.28	%		8.00	%		10.00	%
Tier I Capital (to risk weighted assets)
Company		476,837		11.56	%		4.00	%		6.00	%
NBT Bank		454,476		11.03	%		4.00	%		6.00	%
Tier I Capital (to average assets)
Company		476,837		8.74	%		4.00	%		5.00	%
NBT Bank		454,476		8.35	%		4.00	%		5.00	%