Investments (Details 5) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Realized pretax gains-losses-on the sale of investments excluding temporary impairment losses
Gains	$ 35,515	$ 10,051	$ 14,259
Losses	(4,367)	(6,398)	(2,155)
Net realized investment gain (loss)	31,148	3,653	12,104
Fixed Income Securities [Member]
Realized pretax gains-losses-on the sale of investments excluding temporary impairment losses
Gains	32,644	10,045	14,207
Losses	(3,327)	(6,388)	(1,995)
Net realized investment gain (loss)	29,317	3,657	12,212
Other Investments [Member]
Realized pretax gains-losses-on the sale of investments excluding temporary impairment losses
Gains	2,074	6	52
Losses	(1)	(10)	(160)
Net realized investment gain (loss)	2,073	(4)	(108)
Equity security [Member]
Realized pretax gains-losses-on the sale of investments excluding temporary impairment losses
Gains	797
Losses	(1,039)
Net realized investment gain (loss)	$ (242)