Investments - Schedule of Available-for-sale Securities Reconciliation (Details) (USD $)	6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Available for sale securities:
Amortized Cost	$ 446,986,000	$ 441,562,000
Gross Unrealized Gains	6,132,000	4,358,000
Gross Unrealized Losses	(5,069,000)	(11,333,000)
Fair Value	448,049,000	434,587,000
Percentage of shareholders' equity held by one issuer, maximum	10.00%	10.00%
Available-for-sale securities pledged as collateral, fair value	244,600,000	270,100,000
Mortgage-backed securities, weighted average life	5 years
Obligations of U.S. Government sponsored enterprises
Available for sale securities:
Amortized Cost	92,289,000	93,218,000
Gross Unrealized Gains	806,000	700,000
Gross Unrealized Losses	(124,000)	(388,000)
Fair Value	92,971,000	93,530,000
Obligations of states and political subdivisions
Available for sale securities:
Amortized Cost	49,301,000	49,721,000
Gross Unrealized Gains	1,474,000	983,000
Gross Unrealized Losses	(842,000)	(1,761,000)
Fair Value	49,933,000	48,943,000
Residential mortgage-backed securities
Available for sale securities:
Amortized Cost	305,396,000	298,623,000
Gross Unrealized Gains	3,852,000	2,675,000
Gross Unrealized Losses	(4,103,000)	(9,184,000)
Fair Value	$ 305,145,000	$ 292,114,000