Consolidated Balance Sheets - (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Fixed maturities securities at amortized cost	$ 38,085,000	$ 38,215,000
Equity securities at cost	844,000
Equity securities at cost		659,000
Allowance for uncollectible reinsurance	29,000	29,000
Allowance for uncollectible insurance receivables	42,000	44,000
Accumulated depreciation on property and equipment	216,000	274,000
Due to related parties	23,000	143,000
Due from related parties	$ 8,000	$ 0
Common stock, par value (in usd per share)	$ 2.50	$ 2.50
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	273,040,243	273,040,243
Common stock, shares outstanding (in shares)	271,456,978	271,205,390
Treasury stock, shares (in shares)	1,583,265	1,834,853