Investment Securities - Portfolio of Held-to-Maturity Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Amortized Cost	$ 121,043	$ 141,201
Gross Unrealized Gains	1,815	1,400
Gross Unrealized Losses	370	1,008
Fair Value	122,488	141,593
Obligations of state and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Amortized Cost	43,933	45,914
Gross Unrealized Gains	552	267
Gross Unrealized Losses	38	192
Fair Value	44,447	45,989
GSE mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Amortized Cost	58,420	67,268
Gross Unrealized Gains	1,212	1,080
Gross Unrealized Losses	82	164
Fair Value	59,550	68,184
Collateralized mortgage obligations: residential
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Amortized Cost	11,284	12,709
Gross Unrealized Gains	0	0
Gross Unrealized Losses	250	479
Fair Value	11,034	12,230
Collateralized mortgage obligations: commercial
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Amortized Cost	7,406	15,310
Gross Unrealized Gains	51	53
Gross Unrealized Losses	0	173
Fair Value	$ 7,457	$ 15,190