Accumulated Other Comprehensive Income (Loss) - Details About AOCI Components (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold	$ 1,229	$ 7,136	$ 85,733	$ 64,703
OTTI on investments	(2,388)	(10,295)	(7,676)	(45,027)
Total before tax	2,068		(75,190)
Provision (benefit) for income tax	(897)	(451)	(73,248)	(51,813)
Unrealized gains (losses) on investments
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold	(7,904)		(110,295)
OTTI on investments	2,388		7,676
Total before tax	(5,516)		(102,619)
Provision (benefit) for income tax	3,352		66
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(2,164)		(102,553)
OTTI losses recognized in AOCI
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	7,474		27,099
Cash flow hedge
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	110		330
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	2,068		(75,190)
Provision (benefit) for income tax	3,347		56
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	5,415		(75,134)
Reclassification out of Accumulated Other Comprehensive Income [Member] | OTTI losses recognized in AOCI
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold	6,675		24,562
OTTI on investments	799		2,537
Total before tax	7,474		27,099
Provision (benefit) for income tax	(5)		(10)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	7,469		27,089
Reclassification out of Accumulated Other Comprehensive Income [Member] | Cash flow hedge
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	110		330
Provision (benefit) for income tax	0		0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ 110		$ 330