Investments (Details 7) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Reconciliation of net unrealized investment gains (losses) on fixed maturity securities and equity securities
Reclassification of net realized investment (gains) losses to net income	$ (7,113)	[1],[2]	$ (14,459)	[1],[2]
Fixed Maturity Securities [Member]
Reconciliation of net unrealized investment gains (losses) on fixed maturity securities and equity securities
Beginning of period	146,489		423,004		284,338
Change in unrealized investment gains and losses	195,413		(264,503)		153,758
Reclassification of net realized investment (gains) losses to net income	(5,298)		(12,012)		(15,092)
End of period	336,604		146,489		423,004
Equity Securities [Member]
Reconciliation of net unrealized investment gains (losses) on fixed maturity securities and equity securities
Beginning of period	4,618		720		2,408
Change in unrealized investment gains and losses	4,185		6,345		964
Reclassification of net realized investment (gains) losses to net income	(1,815)		(2,447)		(2,652)
End of period	$ 6,988		$ 4,618		$ 720

[1] All amounts are net of tax.

[2] The pretax amounts reclassified from accumulated other comprehensive income, $10,943 and $22,245, are included in net realized investment gains and losses and the related tax expenses, $3,830 and $7,786, are included in income tax expense in the Consolidated Statements of Operations for the years ended December 31, 2014 and 2013, respectively.