Stock-Based Compensation (Detail) - Summary Of Changes In SARs Outstanding - $ / shares shares in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
SARs
Granted (in shares)	0.3
Weighted- Average Remaining Contractual Term
Granted	2 years 73 days
Stock Appreciation Rights (SARs)
SARs
Outstanding at December 31, 2014 (in shares)	1.4
Granted (in shares)	0.3
Forfeited (in shares)	0.0
Exercised (in shares)	(0.4)
Outstanding at December 31, 2015 (in shares)	1.3	1.4
Vested and exercisable at December 31, 2015 (in shares)	0.5
Per Share Weighted- Average Exercise Price
Outstanding at December 31, 2014 (in Dollars per share)	$ 44.44
Granted (in Dollars per share)	77.92
Exercised (in Dollars per share)	32.53
Outstanding at December 31, 2015 (in Dollars per share)	56.47	$ 44.44
Vested and exercisable at December 31, 2015 (in Dollars per share)	43.51
Per Share Weighted- Average Grant Date Fair Value
Outstanding at December 31, 2014 (in Dollars per share)	13.26
Granted (in Dollars per share)	17.56
Exercised (in Dollars per share)	11.35
Outstanding at December 31, 2015 (in Dollars per share)	14.92	$ 13.26
Vested and exercisable at December 31, 2015 (in Dollars per share)	$ 13.49
Weighted- Average Remaining Contractual Term
Outstanding at December 31, 2014	4 years 5 months 16 days	4 years 4 months 2 days
Granted	6 years 1 month 10 days
Outstanding at December 31, 2015	4 years 5 months 16 days	4 years 4 months 2 days
Vested and exercisable at December 31, 2015	3 years 4 months 17 days