Income Taxes (Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Insurance reserves	$ 171,504	$ 148,115
Other	0	1,966
Deferred tax assets	171,504	150,081
Deferred tax liabilities:
Deferred policy acquisition costs	39,501	45,405
Net unrealized gains on securities	61,294	24,949
Investments	96,385	171,303
Other	7,944
Deferred tax liabilities	205,124	241,657
Deferred tax liabilities	$ (33,620)	$ (91,576)