Securities - Gross unrealized losses and fair value, aggregated by investment category (Details 2) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less Than 12 Months Fair Value	$ 32,372	$ 5,617
Less Than 12 Months Unrealized Losses	744	27
12 Months or More Fair Value	7
12 Months or More Unrealized Losses	1
Total Fair Value	32,379	5,617
Total Unrealized Losses	745	27
U.S. Government sponsored agencies
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less Than 12 Months Fair Value	15,185	3,076
Less Than 12 Months Unrealized Losses	359	13
12 Months or More Fair Value
12 Months or More Unrealized Losses
Total Fair Value	15,185	3,076
Total Unrealized Losses	359	13
Mortgage-backed securities - government sponsored entities
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less Than 12 Months Fair Value	8,063
Less Than 12 Months Unrealized Losses	184
12 Months or More Fair Value	7
12 Months or More Unrealized Losses	1
Total Fair Value	8,070
Total Unrealized Losses	185
State and political subdivisions
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less Than 12 Months Fair Value	9,124	2,541
Less Than 12 Months Unrealized Losses	201	14
12 Months or More Fair Value
12 Months or More Unrealized Losses
Total Fair Value	9,124	2,541
Total Unrealized Losses	$ 201	$ 14