Investments - Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Schedule of Net Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income, operating	$ 25,564	$ 23,697	$ 78,385	$ 71,585
Investment expenses	(1,208)	(1,210)	(3,643)	(3,667)
Investment income net of investment expenses	24,356	22,487	74,742	67,918
Interest expense on surplus note	(4,957)	(3,772)	(13,716)	(8,954)
Net investment income	19,399	18,715	61,026	58,964
Equity Securities [Member]
Schedule of Net Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income, operating	505	514	1,527	1,533
Policy Loans and Other Invested Assets [Member]
Schedule of Net Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income, operating	318	354	998	1,049
Cash and Cash Equivalents [Member]
Schedule of Net Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income, operating	148	51	497	141
Market return on deposit asset underlying 10% insurance agreement [Member]
Schedule of Net Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income, operating	1,058	220	5,443	1,776
Available-for-Sale [Member] | Fixed-maturity Securities [Member]
Schedule of Net Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income, operating	18,578	18,786	56,204	58,132
Held-to-Maturity [Member] | Fixed-maturity Securities [Member]
Schedule of Net Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income, operating	$ 4,957	$ 3,772	$ 13,716	$ 8,954