Statutory Insurance Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statutory Accounting Practices [Line Items]
Statutory Accounting Practices, Statutory Amount Available for Dividend Payments	$ 106,100
Parent Company [Member]
Statutory Accounting Practices [Line Items]
Statutory accounting practices, net gain from operations	106,143	$ 100,013	$ 97,799
Statutory Accounting Practices, Statutory Net Income Amount	100,657	106,009	97,393
Statutory Accounting Practices, Statutory Capital and Surplus, Balance	617,321	603,062
Dividend Payments Restrictions Schedule, Statutory Capital and Surplus	483,838	469,579
Statutory RBC Total adjusted capital	685,721	668,278
Statutory Accounting Practices, Statutory Capital and Surplus Required	$ 125,994	$ 117,284
Statutory RBC Ratio	544.00%	570.00%
Subsidiaries [Member]
Statutory Accounting Practices [Line Items]
Statutory accounting practices, net gain from operations	$ (540)	$ (362)	(433)
Statutory Accounting Practices, Statutory Net Income Amount	(540)	(362)	$ (433)
Statutory Accounting Practices, Statutory Capital and Surplus, Balance	9,175	4,763
Dividend Payments Restrictions Schedule, Statutory Capital and Surplus	(1,625)	(1,037)
Statutory RBC Total adjusted capital	9,191	4,772
Statutory Accounting Practices, Statutory Capital and Surplus Required	$ 173	$ 110
Statutory RBC Ratio	5322.00%	4338.00%