Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Taxes
Current	$ 89,934	$ 70,201	$ 34,090
Deferred	45,371	23,617	33,636
Total income tax provision from continuing operations	135,305	93,818	68,627
Reconciliation between the statutory federal income tax rate and the effective federal income tax rate from continuing operations
Statutory federal income tax rate (as a percent)	35.00%	35.00%	35.00%
Income tax effect of investment income not subject to federal tax (as a percent)	(2.30%)	(2.70%)	(2.20%)
Income tax effect of tax credits (as a percent)	(1.30%)	(2.10%)	(2.90%)
Income tax effect of state income taxes, net of federal benefit (as a percent)	1.20%	0.70%	0.70%
Income tax effect of income tax contingency provisions (as a percent)	0.00%	2.00%	(3.90%)
Income tax effect of other, net (as a percent)	3.60%	(1.20%)	(0.80%)
Effective federal income tax rate from continuing operations (as a percent)	36.20%	31.70%	25.90%
Reconciliation of unrecognized tax benefits
Balance, beginning of year	32,123	35,256	81,390
Additions to tax positions in the current year	6,230	6,557	6,939
Reductions to tax positions in the current year		(420)
Additions to tax positions in the prior year	420	4,785	142
Reductions to tax positions in the prior year	(10,219)	(9,858)	(47,922)
Reductions to tax positions from statutes expiring	(2,704)	(4,197)	(5,253)
Settlements			(40)
Balance, end of year	25,850	32,123	35,256
Federal income taxes
Amount of unrecognized tax benefits if recognized, would impact the annual effective tax rate	25,850	3,832
Anticipated additional increase in unrecognized tax benefits, low end of range	0
Anticipated additional increase in unrecognized tax benefits, high end of range	1,000
Interest and penalties related to the uncertain tax positions	208	2,629	(13,403)
Accrued interest and penalties	$ 4,412	$ 4,204