Significant Accounting Policies Significant Accounting Policies (Details 3)	12 Months Ended
	Dec. 31, 2012
Cash and cash equivalents
Cash and cash equivalents, maximum maturity at the date of purchase (in months)	3 months
Property and casualty unpaid losses and loss expenses
Interest rate used to discount workers compensation loss reserves (as a percent)	2.50%
Agent bonus estimates
Performance period for agent bonuses (in months)	36 months
Period of prior year actual underwriting data used to estimate agent bonuses (in years)	2 years