Stock Option Plans - Stock Option Activity and Related Information (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Shares Under Option, Beginning balance	8.4	8.3	9.0
Shares Under Option, Granted	1.9	1.9	1.7
Shares Under Option, Exercised	(1.4)	(1.6)	(2.3)
Shares Under Option, Forfeited or canceled	(0.1)	(0.2)	(0.1)
Shares Under Option, Ending balance	8.8	8.4	8.3
Shares Under Option, Exercisable at end of period	2.1	2.6	3.8
Shares Under Option, Ending vested and expected to vest	8.7	8.3	8.2
Weighted Average Exercise Price, Beginning balance	$ 35.49	$ 31.35	$ 28.80
Weighted Average Exercise Price, Granted	46.19	46.86	39.17
Weighted Average Exercise Price, Exercised	27.59	28.80	27.11
Weighted Average Exercise Price, Forfeited or canceled		28.36	26.01
Weighted Average Exercised Price, Ending balance	39.25	35.49	31.35
Weighted Average Exercise Price, Exercisable at end of period	28.54	26.91	27.64
Weighted Average Exercise price, Ending vested and expected to vest	$ 39.15	$ 35.38	$ 31.28
Weighted Average Remaining Contractual Term (in years), Ending balance	4 years 1 month 28 days	3 years 11 months 16 days	3 years 7 months 13 days
Weighted Average Remaining Contractual Term (in years), Exercisable at end of period	1 year 11 months 1 day	1 year 10 months 13 days	2 years 1 month 24 days
Weighted Average Remaining Contractual Term (in years), Ending vested and expected to vest	4 years 1 month 17 days	3 years 11 months 5 days	3 years 7 months 2 days
Aggregate Intrinsic Value, Ending Balance	$ 36.7	$ 97.2	$ 129.4
Aggregate Intrinsic Value, Exercisable at end of period	25.9	52.8	72.5
Aggregate Intrinsic Value, Ending vested and expected to vest	$ 36.6	$ 96.6	$ 128.3