Investments - Schedule of Available-for-sale and Held-to-Maturity Securities Reconciliation (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 44,175	$ 45,985
Gross Unrealized Gains	138	150
Gross Unrealized Losses	(212)	(340)
Fair Value	44,101	45,795
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	465,172	396,782
Gross Unrealized Gains	6,500	5,501
Gross Unrealized Losses	(1,176)	(2,137)
Fair Value	470,496	400,146
Obligations of U.S. Government-sponsored enterprises
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	99,015	91,355
Gross Unrealized Gains	1,298	624
Gross Unrealized Losses	0	(153)
Fair Value	100,313	91,826
Obligations of states and political subdivisions
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	40,740	33,997
Gross Unrealized Gains	1,219	1,300
Gross Unrealized Losses	(380)	(416)
Fair Value	41,579	34,881
Agency mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	325,417	271,430
Gross Unrealized Gains	3,983	3,577
Gross Unrealized Losses	(796)	(1,568)
Fair Value	328,604	273,439
Obligations of states and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	14,848	14,900
Gross Unrealized Gains	7	0
Gross Unrealized Losses	(212)	(325)
Fair Value	14,643	14,575
Agency mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	29,327	31,085
Gross Unrealized Gains	131	150
Gross Unrealized Losses	0	(15)
Fair Value	$ 29,458	$ 31,220