Fair Value (Schedule of Additional Information About Significant Unobservable Inputs Used in Fair Valuations of Level 3) (Detail) (USD $) In Millions, unless otherwise specified							6 Months Ended				12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended			6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended		6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended		12 Months Ended			6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Jun. 30, 2014 Corporate Debt Securities [Member] Discount For Small Issue Size Discounted cash flow [Member] Level 3 Maximum	Jun. 30, 2014 Fixed Maturities Discount For Small Issue Size Discounted cash flow [Member] Level 3	Jun. 30, 2014 Fixed Maturities Municipal [Member] Discounted cash flow [Member] Level 3	Dec. 31, 2013 Fixed Maturities Municipal [Member] Discounted cash flow [Member] Level 3	Dec. 31, 2013 Fixed Maturities Municipal [Member] Discount For Small Issue Size Discounted cash flow [Member] Level 3	Jun. 30, 2014 Fixed Maturities Municipal [Member] Discount For Small Issue Size Discounted cash flow [Member] Level 3 Minimum	Dec. 31, 2013 Fixed Maturities Municipal [Member] Discount For Small Issue Size Discounted cash flow [Member] Level 3 Minimum	Jun. 30, 2014 Fixed Maturities Municipal [Member] Discount For Small Issue Size Discounted cash flow [Member] Level 3 Maximum	Dec. 31, 2013 Fixed Maturities Municipal [Member] Discount For Small Issue Size Discounted cash flow [Member] Level 3 Maximum	Jun. 30, 2014 Fixed Maturities Municipal [Member] Discount For Above Market Coupon Discounted cash flow [Member] Level 3	Dec. 31, 2013 Fixed Maturities Municipal [Member] Discount For Above Market Coupon Discounted cash flow [Member] Level 3	Jun. 30, 2014 Fixed Maturities Municipal [Member] Discount For Above Market Coupon Discounted cash flow [Member] Level 3 Minimum	Dec. 31, 2013 Fixed Maturities Municipal [Member] Discount For Above Market Coupon Discounted cash flow [Member] Level 3 Minimum	Jun. 30, 2014 Fixed Maturities Municipal [Member] Discount For Above Market Coupon Discounted cash flow [Member] Level 3 Maximum	Dec. 31, 2013 Fixed Maturities Municipal [Member] Discount For Above Market Coupon Discounted cash flow [Member] Level 3 Maximum	Jun. 30, 2014 Fixed Maturities Corporate Debt Securities [Member] Discounted cash flow [Member] Level 3	Dec. 31, 2013 Fixed Maturities Corporate Debt Securities [Member] Discounted cash flow [Member] Level 3	Jun. 30, 2014 Fixed Maturities Corporate Debt Securities [Member] Discount For Small Issue Size Discounted cash flow [Member] Level 3	Dec. 31, 2013 Fixed Maturities Corporate Debt Securities [Member] Discount For Small Issue Size Discounted cash flow [Member] Level 3	Jun. 30, 2014 Fixed Maturities Corporate Debt Securities [Member] Discount For Small Issue Size Discounted cash flow [Member] Level 3 Minimum	Dec. 31, 2013 Fixed Maturities Corporate Debt Securities [Member] Discount For Small Issue Size Discounted cash flow [Member] Level 3 Minimum	Dec. 31, 2013 Fixed Maturities Corporate Debt Securities [Member] Discount For Small Issue Size Discounted cash flow [Member] Level 3 Maximum	Jun. 30, 2014 Fixed Maturities Corporate Debt Securities [Member] Discount For Above Market Coupon Discounted cash flow [Member] Level 3	Dec. 31, 2013 Fixed Maturities Corporate Debt Securities [Member] Discount For Above Market Coupon Discounted cash flow [Member] Level 3	Jun. 30, 2014 Fixed Maturities Corporate Debt Securities [Member] Discount For Above Market Coupon Discounted cash flow [Member] Level 3 Minimum	Dec. 31, 2013 Fixed Maturities Corporate Debt Securities [Member] Discount For Above Market Coupon Discounted cash flow [Member] Level 3 Minimum	Jun. 30, 2014 Fixed Maturities Corporate Debt Securities [Member] Discount For Above Market Coupon Discounted cash flow [Member] Level 3 Maximum	Dec. 31, 2013 Fixed Maturities Corporate Debt Securities [Member] Discount For Above Market Coupon Discounted cash flow [Member] Level 3 Maximum	Dec. 31, 2013 Fixed Maturities Residential Mortgage Backed Securities [Member] Discounted cash flow [Member] Level 3	Dec. 31, 2013 Fixed Maturities Residential Mortgage Backed Securities [Member] Discount For Small Issue Size Discounted cash flow [Member] Level 3	Jun. 30, 2014 Fixed Maturities Commercial Mortgage Backed Securities [Member] Discounted cash flow [Member] Level 3	Dec. 31, 2013 Fixed Maturities Commercial Mortgage Backed Securities [Member] Discounted cash flow [Member] Level 3	Jun. 30, 2014 Fixed Maturities Commercial Mortgage Backed Securities [Member] Discount For Small Issue Size Discounted cash flow [Member] Level 3	Dec. 31, 2013 Fixed Maturities Commercial Mortgage Backed Securities [Member] Discount For Small Issue Size Discounted cash flow [Member] Level 3	Jun. 30, 2014 Fixed Maturities Commercial Mortgage Backed Securities [Member] Discount For Above Market Coupon Discounted cash flow [Member] Level 3	Dec. 31, 2013 Fixed Maturities Commercial Mortgage Backed Securities [Member] Discount For Above Market Coupon Discounted cash flow [Member] Level 3	Jun. 30, 2014 Fixed Maturities Commercial Mortgage Backed Securities [Member] Discount For Above Market Coupon Discounted cash flow [Member] Level 3 Minimum	Dec. 31, 2013 Fixed Maturities Commercial Mortgage Backed Securities [Member] Discount For Above Market Coupon Discounted cash flow [Member] Level 3 Minimum	Jun. 30, 2014 Fixed Maturities Commercial Mortgage Backed Securities [Member] Discount For Above Market Coupon Discounted cash flow [Member] Level 3 Maximum	Dec. 31, 2013 Fixed Maturities Commercial Mortgage Backed Securities [Member] Discount For Above Market Coupon Discounted cash flow [Member] Level 3 Maximum	Jun. 30, 2014 Fixed Maturities Commercial Mortgage Backed Securities [Member] Discount For Credit Stress Discounted cash flow [Member] Level 3	Dec. 31, 2013 Fixed Maturities Commercial Mortgage Backed Securities [Member] Discount For Credit Stress Discounted cash flow [Member] Level 3	Jun. 30, 2014 Fixed Maturities Commercial Mortgage Backed Securities [Member] Discount For Lease Structure Discounted cash flow [Member] Level 3	Dec. 31, 2013 Fixed Maturities Commercial Mortgage Backed Securities [Member] Discount For Lease Structure Discounted cash flow [Member] Level 3	Jun. 30, 2014 Other securities Discounted cash flow [Member] Level 3	Dec. 31, 2013 Other securities Discounted cash flow [Member] Level 3	Jun. 30, 2014 Equity Securities Market comparables [Member] Level 3	Dec. 31, 2013 Equity Securities Market comparables [Member] Level 3
Fair Value [Line Items]
Fair value measurement weighted average market multiples																																																					1.0	1.3
Fair Value	$ 67.3	$ 70.1	$ 104.2	$ 103.9	$ 105.6	$ 102.7			$ 26.8	$ 25.6												$ 12.9	$ 12.8												$ 0.5		$ 22.5	$ 22.9													$ 3.6	$ 3.6	$ 1.1	$ 38.5
Weighted average rate							1.00%	2.10%			2.30%	0.60%	1.00%	4.00%	4.00%	0.40%	0.50%	0.30%	0.30%	1.00%	1.00%			0.50%	0.50%	0.30%	0.30%	1.00%	0.60%	0.60%	0.30%	0.30%	0.80%	0.80%		0.50%			0.50%	0.50%	0.50%	0.60%	0.50%	0.50%	0.80%	0.80%	0.50%	0.50%	0.30%	0.30%	18.00%	18.00%