CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Fixed maturities, amortized cost	$ 4,602,457	$ 4,684,148
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	359,395,000	340,097,000
Common stock, shares outstanding (in shares)	345,474,000	339,657,000
Treasury stock, shares at cost (in shares)	13,921,000	440,000