Investments - Schedule of Unrealized Loss on Investments (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Vaule	$ 35,950	$ 207,361
Less than 12 months, Unrealized Losses	164	8,678
12 months or more, Fair Value	175,289	28,605
12 months or more, Unrealized Losses	5,403	2,655
Total, Fair Value	211,239	235,966
Total, Unrealized Losses	5,567	11,333
Obligations of U.S. Government-sponsored enterprises
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Vaule	5,454	30,221
Less than 12 months, Unrealized Losses	7	388
12 months or more, Fair Value	24,813	0
12 months or more, Unrealized Losses	182	0
Total, Fair Value	30,267	30,221
Total, Unrealized Losses	189	388
Obligations of states and political subdivisions
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Vaule	1,092	17,141
Less than 12 months, Unrealized Losses	18	952
12 months or more, Fair Value	14,143	7,168
12 months or more, Unrealized Losses	681	809
Total, Fair Value	15,235	24,309
Total, Unrealized Losses	699	1,761
Agency mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Vaule	29,404	159,999
Less than 12 months, Unrealized Losses	139	7,338
12 months or more, Fair Value	136,333	21,437
12 months or more, Unrealized Losses	4,540	1,846
Total, Fair Value	165,737	181,436
Total, Unrealized Losses	$ 4,679	$ 9,184