Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Tax Contingency [Line Items]
Current expense	$ 1,387	$ 27,585	$ 7,943	$ 58,845
Deferred expense	15,900	(5,897)	50,148	6,128
Total income tax provision	17,287	$ 21,688	$ 58,091	$ 64,973
Reconciliation between the statutory federal income tax rate and the effective income tax rate from continuing operations
Statutory federal income tax rate			21.00%	35.00%
Investment income not subject to federal tax			(2.30%)	(3.90%)
Tax credits			(0.60%)	(0.30%)
State income taxes, net of federal benefit			2.70%	2.80%
Other, net			0.20%	(0.50%)
Effective income tax rate			21.00%	33.10%
Reconciliation of unrecognized tax benefits
Increase (decrease) in unrecognized tax benefit			$ (11,434)	$ 4,694
Minimum
Reconciliation of unrecognized tax benefits
Additional increase to unrecognized tax benefits	1,000		1,000
Maximum
Reconciliation of unrecognized tax benefits
Additional increase to unrecognized tax benefits	$ 3,000		$ 3,000