Investments (Details 5) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Realized pretax gains (losses) on the sale of investments
Gains	$ 78,476	$ 46,422	$ 35,515
Losses	(12,106)	(4,392)	(4,367)
Net realized investment gain	66,370	42,030	31,148
Fixed Maturity Securities [Member]
Realized pretax gains (losses) on the sale of investments
Gains	9,805	20,191	32,644
Losses	(5,268)	(1,174)	(3,327)
Net realized investment gain	4,537	19,017	29,317
Equity Securities [Member]
Realized pretax gains (losses) on the sale of investments
Gains	68,671	20,886	797
Losses	(6,838)	(3,218)	(1,039)
Net realized investment gain	61,833	17,668	(242)
Others [Member]
Realized pretax gains (losses) on the sale of investments
Gains	0	5,345	2,074
Losses	0	0	(1)
Net realized investment gain	$ 0	$ 5,345	$ 2,073