Statements of Financial Position (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Fixed maturities, available-for-sale, amortized cost	$ 9,818,298	$ 2,433,626
Equity securities, available-for-sale, cost	$ 365	$ 14
Common stock, par value (in dollars per share)	$ 100	$ 100
Common stock, shares authorized	25,000	25,000
Common stock, shares issued	25,000	25,000
Common stock, shares outstanding	25,000	25,000