Accumulated Other Comprehensive Income (Loss) - Details About AOCI Components (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold	$ 41,147	$ 41,768
OTTI on investments	(3,727)	(18,565)
Total before tax	(36,400)
Tax (benefit) expense	(43,479)	(21,550)
Unrealized gains (losses) on investments
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	(41,695)
OTTI losses recognized in AOCI
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	5,185
Cash flow hedge
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	110
Reclassification out of Accumulated Other Comprehensive Income
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	(36,400)
Tax (benefit) expense	271
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(36,129)
Reclassification out of Accumulated Other Comprehensive Income | Unrealized gains (losses) on investments
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold	(45,422)
OTTI on investments	3,727
Total before tax	(41,695)
Tax (benefit) expense	274
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(41,421)
Reclassification out of Accumulated Other Comprehensive Income | OTTI losses recognized in AOCI
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold	4,275
OTTI on investments	910
Total before tax	5,185
Tax (benefit) expense	(3)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	5,182
Reclassification out of Accumulated Other Comprehensive Income | Cash flow hedge
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	110
Tax (benefit) expense	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ 110