Reinsurance (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Transatlantic Reinsurance Company [Member]
Reinsurers With Net Recoverable Balances Greater Than 25 Million [Line Items]
Total recoverables	$ 157,349	$ 172,165
Total credits	8,063	18,196
Net recoverables	149,286	153,969
Axis Reinsurance Company [Member]
Reinsurers With Net Recoverable Balances Greater Than 25 Million [Line Items]
Total recoverables	103,836	92,562
Total credits	12,593	11,983
Net recoverables	91,243	80,579
Hannover Rueckversicherungs Ag [Member]
Reinsurers With Net Recoverable Balances Greater Than 25 Million [Line Items]
Total recoverables	107,125	128,518
Total credits	18,468	20,559
Net recoverables	88,657	107,959
Ace Property And Casualty Insurance Company [Member]
Reinsurers With Net Recoverable Balances Greater Than 25 Million [Line Items]
Total recoverables	58,996	67,742
Total credits	5,552	4,267
Net recoverables	53,444	63,475
Swiss Reinsurance America Corporation [Member]
Reinsurers With Net Recoverable Balances Greater Than 25 Million [Line Items]
Total recoverables	45,756
Total credits	5,314
Net recoverables	40,442
Arch Reinsurance Company [Member]
Reinsurers With Net Recoverable Balances Greater Than 25 Million [Line Items]
Total recoverables	37,172	40,481
Total credits	602	3,693
Net recoverables	$ 36,570	$ 36,788