Reinsurance (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013
E&S Commercial [Member]
Retention for reinsurance losses	$ 1.0
Proportional reinsurance retention, percentage	10.00%
Concentration of ceded credit risk, percentage	100.00%
Concentration of ceded credit risk remaining, percentage	90.00%
Excess and Umbrella Business Unit [Member]
Proportional reinsurance retention, percentage	20.00%
Concentration of ceded credit risk, percentage	80.00%
Standard Commercial Segment [Member]
Proportional reinsurance cede risk, percentage	100.00%
Professional Liability [Member]
Proportional reinsurance retention, percentage	50.00%
Concentration of ceded credit risk, percentage	50.00%
Professional Liability [Member] | Prior to June 1, 2012 [Member]
Proportional reinsurance retention, percentage	40.00%
Concentration of ceded credit risk, percentage	60.00%
Hallmark County Mutual [Member]
Proportional reinsurance retention, percentage	100.00%
Catastrophe [Member]
Retention for reinsurance losses	6.0
Catastrophe [Member] | All States [Member]
Retention for reinsurance losses	15.0
Catastrophe losses risk value	15.0
Reinsurers reimbursement, percentage	100.00%
Reinsurers reimbursement retention, maximum limit	25.0
Reinsurers reimbursement retention, aggregate limit	50.0
Catastrophe [Member] | Texas [Member]
Reinsurers reimbursement, percentage	100.00%
Reinsurers reimbursement retention for each disaster occurrence	9.0
Other Property Catastrophe [Member] | Texas [Member]
Reinsurers reimbursement, percentage	87.50%
Commercial Property [Member]
Retention for reinsurance losses	1.0
Commercial property risk value	6.0
Reinsurers reimbursement retention for any one disaster occurrence	10.0
Reinsurers reimbursement retention for each disaster occurrence	5.0
Reinsurers reimbursement retention, aggregate limit	30.0
Commercial Liability Risk [Member]
Retention for reinsurance losses	1.0
Reinsurers reimbursement retention for each disaster occurrence	5.0
Workers Compensation Risks [Member]
Retention for reinsurance losses	1.0
Reinsurers reimbursement, percentage	100.00%
Reinsurers reimbursement retention for each disaster occurrence	14.0
Reinsurers reimbursement retention, maximum limit	10.0
Reinsurers reimbursement retention, aggregate limit	28.0
Aircraft Hull [Member]
Retention for reinsurance losses	1.0
Reinsurers reimbursement retention for each disaster occurrence	5.5
Liability Loss [Member]
Retention for reinsurance losses	1.0
Reinsurers reimbursement retention for each disaster occurrence	5.5
Airport Liability Loss [Member]
Retention for reinsurance losses	1.0
Reinsurers reimbursement retention for each disaster occurrence	4.0
Personal Property [Member]
Proportional reinsurance cede risk, percentage	60.00%
Minimum [Member] | E&S Commercial [Member]
Retention for reinsurance losses	$ 1.0