Investments (Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Net Investment Income [Line Items]
Net investment income earned	$ 32,061	$ 34,292	$ 91,208	$ 106,600
Fixed Income Securities [Member]
Net Investment Income [Line Items]
Net investment income earned	30,601	30,706	92,227	95,515
Equity Securities [Member]
Net Investment Income [Line Items]
Net investment income earned	2,370	1,909	6,546	5,094
Short-Term Investments [Member]
Net Investment Income [Line Items]
Net investment income earned	24	15	72	48
Other Investments [Member]
Net Investment Income [Line Items]
Net investment income earned	1,337	3,906	(781)	12,677
Investment Expenses [Member]
Net Investment Income [Line Items]
Net investment income earned	$ (2,271)	$ (2,244)	$ (6,856)	$ (6,734)