Investments (Schedule Of Contractual Maturities Of Fixed Maturity Securities Available-For-Sale) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Investments [Abstract]
Due in one year or less, Amortized cost	$ 649.0	$ 486.2
Due after one year through five years, Amortized cost	3,060.8	2,974.5
Due after five years through ten years, Amortized Cost	2,847.9	2,497.5
Due after ten years, Amortized Cost	832.3	853.7
Total fixed maturity securities-available-for-sale, Amortized Cost	7,390.0	6,811.9
Due in one year or less, Fair Value	658.0	495.1
Due after one year through five years, Fair Value	3,215.4	3,168.9
Due after five years through ten years, Fair Value	2,916.7	2,524.6
Due after ten years, Fair Value	983.6	931.9
Total fixed maturity securities-available-for-sale	$ 7,773.7	$ 7,120.5