Condensed Balance Sheets (Parenthetical) (USD $) In Millions, except Share data	Jun. 30, 2011	Dec. 31, 2010
Condensed Balance Sheets
Fixed maturities, available-for-sale, amortized cost (in dollars)	$ 20,324.7	$ 20,237.9
Equity securities, available-for-sale, cost (in dollars)	130.9	139.5
Securities pledged, amortized cost (in dollars)	$ 721.0	$ 886.6
Common stock, shares authorized	250,000	250,000
Common stock, shares issued	250,000	250,000
Common stock, shares outstanding	250,000	250,000
Common stock, per share value (in dollars per share)	$ 10	$ 10