Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Statement Of Financial Position [Abstract]
Fixed maturities, available for sale, amortized cost	$ 12,267,490	$ 11,963,406	[1]
Equity securities, cost	875	14,875	[1]
Long-term debt, fair value	$ 1,145,499	$ 1,191,320	[1]
Preferred stock, par value	$ 1	$ 1	[1]
Preferred stock, shares authorized	5,000,000	5,000,000	[1]
Preferred stock, shares outstanding	0	0	[1]
Common stock, par value	$ 1	$ 1	[1]
Common stock, shares authorized	320,000,000	320,000,000	[1]
Common stock, shares issued	105,812,123	105,812,123	[1]
Common stock, shares held in treasury	15,058,017	11,576,487	[1]

[1] Derived from audited financial statements