Investments, Contractual Maturities of Available-for-sale Fixed Maturity Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Amortized Cost [Abstract]
Due in one year or less, Amortized Cost	$ 10,283
Due after one year through five years, Amortized Cost	67,670
Due after five years through ten years, Amortized Cost	55,725
Due after ten years, Amortized Cost	118,705
Total fixed maturities, Amortized Cost	514,237	$ 422,255
Estimated Fair Value [Abstract]
Due in one year or less, Estimated Fair Value	10,252
Due after one year through five years, Estimated Fair Value	67,426
Due after five years through ten years, Estimated Fair Value	56,235
Due after ten years, Estimated Fair Value	118,050
Total fixed maturities, Estimated Fair Value	510,251	$ 425,191
Asset-backed Securities [Member]
Amortized Cost [Abstract]
Without single maturity date, Amortized Cost	151,137
Estimated Fair Value [Abstract]
Without single maturity date, Estimated Fair Value	149,867
Residential Mortgage-backed Securities [Member]
Amortized Cost [Abstract]
Without single maturity date, Amortized Cost	110,717
Estimated Fair Value [Abstract]
Without single maturity date, Estimated Fair Value	$ 108,421