Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Fixed maturities, available-for-sale, amortized cost (in dollars)	$ 18,848,230	$ 20,007,462
Fixed maturities, held for trading, amortized cost (in dollars)	316,261	612,899
Mortgage loans on real estate, allowances (in dollars)	2,882	2,890
Short-term investments, available-for-sale, amortized cost (in dollars)	$ 2,413,192	$ 267,026
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, number of shares authorized	50,000,000	50,000,000
Preferred stock, number of shares issued	0	0
Preferred stock, number of shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, number of shares authorized	50,000,000	50,000,000
Common stock, number of shares issued	7,232,986	7,232,986
Common stock, number of shares outstanding	7,232,986	7,232,986