Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Current	$ 32,031	$ 76,842	$ 80,859
Deferred	53,481	21,682	75,044
Total income tax provision	$ 85,512	$ 98,524	$ 155,903
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	(3.00%)	(3.00%)	(1.80%)
Tax credits	(6.90%)	(0.20%)	(0.30%)
State income taxes, net of federal benefit	2.30%	3.20%	1.00%
Income tax contingency provisions	0.00%	0.00%	(1.20%)
Other, net	(0.40%)	(0.90%)	0.20%
Effective federal income tax rate	27.00%	34.10%	32.90%
Reconciliation of unrecognized tax benefits
Balance, beginning of year	$ 23,093	$ 26,890	$ 21,154
Additions to tax positions in the current year	0	1,383	13,931
Additions to tax positions in the prior year	1,902	50	0
Reductions to tax positions from statutes expiring	(7,727)	(5,230)	(8,195)
Balance, end of year	$ 17,268	$ 23,093	$ 26,890