Fair Value (Schedule Of Additional Information About Significant Unobservable Inputs Used In Fair Valuations Of Level 3) (Details) (USD $) In Millions, unless otherwise specified													3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010	Mar. 31, 2012 Equity Securities [Member]	Dec. 31, 2011 Equity Securities [Member]	Mar. 31, 2011 Equity Securities [Member]	Dec. 31, 2010 Equity Securities [Member]	Mar. 31, 2012 Level 3 [Member] Municipal [Member]	Mar. 31, 2012 Level 3 [Member] Corporate [Member]	Mar. 31, 2012 Level 3 [Member] Commercial Mortgage-Backed [Member]	Mar. 31, 2012 Level 3 [Member] Asset-Backed [Member]	Mar. 31, 2012 Level 3 [Member] Equity Securities [Member]	Mar. 31, 2012 Discount For Small Issue Size [Member] Discounted Cash Flow [Member] Level 3 [Member] Municipal [Member]	Mar. 31, 2012 Discount For Small Issue Size [Member] Discounted Cash Flow [Member] Level 3 [Member] Corporate [Member]	Mar. 31, 2012 Discount For Small Issue Size [Member] Discounted Cash Flow [Member] Level 3 [Member] Commercial Mortgage-Backed [Member]	Mar. 31, 2012 Discount For Small Issue Size [Member] Discounted Cash Flow [Member] Level 3 [Member] Asset-Backed [Member]	Mar. 31, 2012 Discount For Above-Market Coupon [Member] Discounted Cash Flow [Member] Level 3 [Member] Municipal [Member]	Mar. 31, 2012 Discount For Above-Market Coupon [Member] Discounted Cash Flow [Member] Level 3 [Member] Corporate [Member]	Mar. 31, 2012 Discount For Above-Market Coupon [Member] Discounted Cash Flow [Member] Level 3 [Member] Commercial Mortgage-Backed [Member]	Mar. 31, 2012 Discount For Above-Market Coupon [Member] Discounted Cash Flow [Member] Level 3 [Member] Asset-Backed [Member]	Mar. 31, 2012 Discount For Credit Stress [Member] Discounted Cash Flow [Member] Level 3 [Member] Corporate [Member]	Mar. 31, 2012 Discount For Credit Stress [Member] Discounted Cash Flow [Member] Level 3 [Member] Commercial Mortgage-Backed [Member]	Mar. 31, 2012 Discount For Lease Structure [Member] Discounted Cash Flow [Member] Level 3 [Member] Asset-Backed [Member]	Mar. 31, 2012 Discount For Long Maturity [Member] Discounted Cash Flow [Member] Level 3 [Member] Municipal [Member]	Mar. 31, 2012 Discount For Long Maturity [Member] Discounted Cash Flow [Member] Level 3 [Member] Corporate [Member]	Mar. 31, 2012 Discount For Long Maturity [Member] Discounted Cash Flow [Member] Level 3 [Member] Asset-Backed [Member]
Fair Value [Line Items]
Fair Value	$ 96.6	$ 98.9	$ 72.4	$ 67.5	$ 21.4	$ 23.4	$ 2.9	$ 2.9	$ 17.0	$ 28.7	$ 4.5	$ 24.3	$ 21.4
Discount rate													0.87%			0.50%				0.50%			1.00%	0.30%	0.50%	0.50%
Discount rate, minimum														1.00%	0.30%		0.30%	0.30%	0.30%		0.30%	2.00%					0.50%
Discount rate, maximum														4.00%	3.00%		0.50%	1.00%	2.00%		1.00%	3.00%					0.80%
Weighted average rate													0.87%	3.10%	0.50%	0.50%	0.50%	0.50%	0.80%	0.50%	0.40%	2.00%	1.00%	0.30%	0.50%	0.50%	0.70%