Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Current	$ 80,859	$ 82,878	$ 89,934
Deferred	75,044	(24,087)	45,371
Total income tax provision	155,903	58,791	135,305
Reconciliation between the statutory federal income tax rate and the effective federal income tax rate from continuing operations
Statutory federal income tax rate	35.00%	35.00%	35.00%
Investment income not subject to federal tax	(1.80%)	(4.60%)	(2.30%)
Tax credits	(0.30%)	(2.00%)	(1.30%)
State income taxes, net of federal benefit	1.00%	3.30%	1.20%
Income tax contingency provisions	(1.20%)	(0.40%)	0.00%
Other, net	0.20%	0.00%	3.60%
Effective federal income tax rate	32.90%	31.30%	36.20%
Reconciliation of unrecognized tax benefits
Balance, beginning of year	21,154	25,850	32,123
Additions to tax positions in the current year	13,931	0	6,230
Additions to tax positions in the prior year	0	1,497	420
Reductions to tax positions in the prior year	0	(180)	(10,219)
Reductions to tax positions from statutes expiring	(8,195)	(6,013)	(2,704)
Balance, end of year	26,890	21,154	25,850
Federal income taxes
Unrecognized tax benefits	26,890	21,154	25,850
Amount of unrecognized tax benefits if recognized, would impact the annual effective tax rate	545
Anticipated additional increase in unrecognized tax benefits, low end of range	6,000
Anticipated additional increase in unrecognized tax benefits, high end of range	7,000
Interest and penalties related to the uncertain tax positions	(2,916)	(286)	208
Accrued interest and penalties	$ 1,210	$ 4,126