Realized and Unrealized Investment Gains (Losses) (Realized and unrealized investmetns gains(losses)) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Realized and Unrealized Investment Gains Losses [Line Items]
Fixed maturity securities, gains	$ 7,427	$ 10,110	$ 13,032	$ 33,174
Fixed maturity securities, losses	0	(1,480)	(3,965)	(4,420)
Equity securities available for sale	32,139	4,471	74,846	4,596
Investment funds	(112)	(4,793)	1,155	(5,253)
Real estate	(364)	(464)	2,936	4,560
Other	1,363	(1,529)	4,797	(885)
Net realized gains on investments sales	40,453	6,315	92,801	31,772
Other-than-temporary impairments	0	0	0	(18,114)
Net investment gains	40,453	6,315	92,801	13,658
Income tax expense	(14,159)	(2,210)	(32,480)	(4,780)
After-tax net realized investment gains	$ 26,294	$ 4,105	$ 60,321	8,878
Common stock
Realized and Unrealized Investment Gains Losses [Line Items]
Other-than-temporary impairments				$ (18,100)