Investments (Net Realized Investments Gains) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Investments [Line Items]
Net realized investment gains (losses)	$ 81,184	$ (11,422)	$ 66,380
Swap [Member]
Investments [Line Items]
Net realized investment gains (losses)	(2,969)	2,176	0
Fixed Maturity Securities [Member]
Investments [Line Items]
Net realized investment gains (losses)	74,489	(95,225)	47,707
Equity Securities [Member]
Investments [Line Items]
Net realized investment gains (losses)	8,715	80,910	16,679
Short-Term Investments [Member]
Investments [Line Items]
Net realized investment gains (losses)	(2,470)	(1,059)	(686)
Option [Member]
Investments [Line Items]
Net realized investment gains (losses)	$ 3,419	$ 1,776	$ 2,680