Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Current expense	$ 18,300	$ 32,483	$ 31,260	$ 43,124
Deferred expense	7,868	7,227	12,026	20,624
Total income tax provision	26,168	39,710	$ 43,286	$ 63,748
Reconciliation between the statutory federal income tax rate and the effective income tax rate from continuing operations
Statutory federal income tax rate			35.00%	35.00%
Investment income not subject to federal tax			(3.40%)	(2.70%)
Tax credits			(0.60%)	(8.80%)
State income taxes, net of federal benefit			2.50%	2.80%
Other, net			0.30%	0.70%
Effective income tax rate			33.80%	27.00%
Reconciliation of unrecognized tax benefits
Increase in unrecognized tax benefit			$ 3,714	$ 2,477
Additional decrease to unrecognized tax benefits	$ 7,000	$ 9,000	$ 7,000	$ 9,000