Investment Securities - Portfolio of Held-to-Maturity Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Amortized Cost	$ 126,529	$ 141,201
Gross Unrealized Gains	1,152	1,400
Gross Unrealized Losses	832	1,008
Fair Value	126,849	141,593
Obligations of state and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Amortized Cost	44,128	45,914
Gross Unrealized Gains	260	267
Gross Unrealized Losses	247	192
Fair Value	44,141	45,989
GSE mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Amortized Cost	61,609	67,268
Gross Unrealized Gains	868	1,080
Gross Unrealized Losses	214	164
Fair Value	62,263	68,184
Collateralized mortgage obligations: residential
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Amortized Cost	11,778	12,709
Gross Unrealized Gains	0	0
Gross Unrealized Losses	370	479
Fair Value	11,408	12,230
Collateralized mortgage obligations: commercial
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Amortized Cost	9,014	15,310
Gross Unrealized Gains	24	53
Gross Unrealized Losses	1	173
Fair Value	$ 9,037	$ 15,190