Unaudited Interim Consolidated Statements of Financial Position (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Fixed maturities, available for sale, amortized cost	$ 5,188,994	$ 4,941,944
Fixed maturities, trading, amortized cost	38,279	38,279
Equity securities, cost	37,718	32,694
Other invested assets, at fair value	$ 66,160	$ 726
Common stock, par value (in dollars per share)	$ 10	$ 10
Common stock, shares authorized	1,000,000	1,000,000
Common stock, shares issued	250,000	250,000
Common stock, shares outstanding	250,000	250,000