CONSOLIDATED CONDENSED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Fixed maturities at fair value, amortized cost	$ 54,555,431	$ 41,153,551
Fixed maturities at amortized cost, fair value	2,577,841	2,776,327
Equity securities, cost	663,338	740,813
Mortgage loans, related to securitizations	505	226,409
Investment real estate, accumulated depreciation	219	132
Other intangibles, accumulated amortization	183,268	140,368
Property and equipment, accumulated depreciation	$ 30,569	$ 22,926
Common Stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common Stock, shares authorized (in shares)	5,000	5,000
Common Stock, shares issued (in shares)	1,000	1,000
Net unrealized gains (losses) on investments, income tax	$ 317,185	$ 6,883
Net unrealized (losses) gains relating to other-than-temporary impaired investments for which a portion has been recognized in earnings, income tax	0	(6)
Accumulated loss - derivatives, income tax	1,180	198
Postretirement benefits liability adjustment, income tax	$ 0	$ (3,469)