OPERATING SEGMENT INFORMATION (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Revenue by major product
Net premiums earned	$ 161,132	$ 144,151
Casualty
Revenue by major product
Net premiums earned	90,977	72,969
Casualty | Commercial and personal umbrella
Revenue by major product
Net premiums earned	24,756	18,950
Casualty | General liability
Revenue by major product
Net premiums earned	19,932	20,777
Casualty | Commercial transportation
Revenue by major product
Net premiums earned	14,511	9,934
Casualty | Professional services
Revenue by major product
Net premiums earned	12,861	9,009
Casualty | P&C package business
Revenue by major product
Net premiums earned	8,283	7,421
Casualty | Executive products
Revenue by major product
Net premiums earned	4,684	4,716
Casualty | Medical professional liability
Revenue by major product
Net premiums earned	3,700	750
Casualty | Other casualty
Revenue by major product
Net premiums earned	2,250	1,412
Property
Revenue by major product
Net premiums earned	43,318	44,981
Property | Commercial property
Revenue by major product
Net premiums earned	20,433	19,616
Property | Marine
Revenue by major product
Net premiums earned	12,201	14,614
Property | Property reinsurance
Revenue by major product
Net premiums earned	3,361	5,272
Property | Crop reinsurance
Revenue by major product
Net premiums earned	1,186	1,267
Property | Other property
Revenue by major product
Net premiums earned	6,137	4,212
Surety
Revenue by major product
Net premiums earned	26,837	26,201
Surety | Miscellaneous
Revenue by major product
Net premiums earned	9,482	9,481
Surety | Contract
Revenue by major product
Net premiums earned	6,761	6,459
Surety | Commercial
Revenue by major product
Net premiums earned	6,134	5,711
Surety | Oil and Gas
Revenue by major product
Net premiums earned	$ 4,460	$ 4,550