Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 10.7	$ 6.7	$ 6.6
Amounts Recorded in Earnings	5.7	2.7	2.7
Adjustments	(3.1)	1.3	(2.6)
Balance at End of Year	13.3	10.7	6.7
Allowance for Estimated Policy Cancellations [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	6.8	4.2	4.0
Amounts Recorded in Earnings	3.6	(0.2)	(0.2)
Adjustments	(3.0)	2.8	0.4
Balance at End of Year	7.4	6.8	4.2
Accumulated Amortization of Expiration Lists, Noncompete Agreements and Trade Names [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	758.8	544.1	419.3
Amounts Recorded in Earnings	240.3	189.5	125.2
Adjustments	(15.2)	25.2	(0.4)
Balance at End of Year	$ 983.9	$ 758.8	$ 544.1