Allowance for Loan and Lease Losses - Loans that were Evaluated for Impairment by Loan Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Sep. 30, 2015
Unpaid principal balance [Abstract]
With no related allowance recorded	$ 14,004	$ 11,326
With an allowance recorded	9,424	6,437
Recorded investment [Abstract]
With no related allowance recorded	12,804	8,069
With an allowance recorded	3,274	2,049
Related allowance [Abstract]
Related allowance	1,041	322
Average recorded investment [Abstract]
With no related allowance recorded	13,975
With an allowance recorded	2,479
Interest income recognized [Abstract]
With no related allowance recorded	377
Commercial real estate [Member]
Unpaid principal balance [Abstract]
With no related allowance recorded	6,632	4,567
With an allowance recorded	926
Recorded investment [Abstract]
With no related allowance recorded	6,113	4,040
With an allowance recorded	682
Related allowance [Abstract]
Related allowance	200
Average recorded investment [Abstract]
With no related allowance recorded	5,089
With an allowance recorded	529
Interest income recognized [Abstract]
With no related allowance recorded	98
Construction and land development [Member]
Unpaid principal balance [Abstract]
With no related allowance recorded	894
With an allowance recorded		546
Recorded investment [Abstract]
With no related allowance recorded	683
With an allowance recorded		290
Related allowance [Abstract]
Related allowance		145
Average recorded investment [Abstract]
With no related allowance recorded	2,233
With an allowance recorded	145
Interest income recognized [Abstract]
With no related allowance recorded	71
Commercial and industrial [Member]
Unpaid principal balance [Abstract]
With no related allowance recorded	5,358	5,303
With an allowance recorded	2,500
Recorded investment [Abstract]
With no related allowance recorded	5,118	3,024
With an allowance recorded	728
Related allowance [Abstract]
Related allowance	301
Average recorded investment [Abstract]
With no related allowance recorded	5,786
With an allowance recorded	688
Interest income recognized [Abstract]
With no related allowance recorded	208
Residential real estate [Member]
Unpaid principal balance [Abstract]
With an allowance recorded	1,068	1,021
Recorded investment [Abstract]
With an allowance recorded	959	918
Related allowance [Abstract]
Related allowance	28	28
Average recorded investment [Abstract]
With an allowance recorded	864
Leases [Member]
Unpaid principal balance [Abstract]
With an allowance recorded	95	640
Recorded investment [Abstract]
With an allowance recorded	95	640
Related allowance [Abstract]
Related allowance	80	131
Average recorded investment [Abstract]
With an allowance recorded	108
Tax certificates [Member]
Unpaid principal balance [Abstract]
With no related allowance recorded	1,120	1,456
With an allowance recorded	4,835	4,230
Recorded investment [Abstract]
With no related allowance recorded	890	1,005
With an allowance recorded	810	201
Related allowance [Abstract]
Related allowance	432	$ 18
Average recorded investment [Abstract]
With no related allowance recorded	867
With an allowance recorded	$ 145