Accumulated Other Comprehensive Income (Loss) - Changes in AOCI, net of tax (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	$ 1,520,011
OCI before Reclassifications	(91,224)
Amounts reclassified from AOCI	(36,400)
Tax (benefit) expense	12,723
Net current period OCI - net of tax	(114,901)
Ending balance, net of tax	1,405,110
Unrealized gains (losses) on investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	1,597,823
OCI before Reclassifications	(87,688)
Amounts reclassified from AOCI	(41,695)
Tax (benefit) expense	12,726
Net current period OCI - net of tax	(116,657)
Ending balance, net of tax	1,481,166
OTTI losses recognized in AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	(121,371)
OCI before Reclassifications	0
Amounts reclassified from AOCI	5,185
Tax (benefit) expense	(3)
Net current period OCI - net of tax	5,182
Ending balance, net of tax	(116,189)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	69,391
OCI before Reclassifications	(3,921)
Amounts reclassified from AOCI	0
Tax (benefit) expense	0
Net current period OCI - net of tax	(3,921)
Ending balance, net of tax	65,470
Underfunded pension liability
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	(27,506)
OCI before Reclassifications	385
Amounts reclassified from AOCI	0
Tax (benefit) expense	0
Net current period OCI - net of tax	385
Ending balance, net of tax	(27,121)
Cash flow hedge
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	1,674
OCI before Reclassifications	0
Amounts reclassified from AOCI	110
Tax (benefit) expense	0
Net current period OCI - net of tax	110
Ending balance, net of tax	$ 1,784