Stock-Based Compensation (Detail) - Summary Of Changes In SARs Outstanding - $ / shares shares in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Weighted-Average Remaining Contractual Term (in years)
Granted	2 years 3 months 18 days
Stock Appreciation Rights (SARs)
SARs
Outstanding at December 31, 2015 (in shares)	1.3
Granted (in shares)	0.4
Forfeited (in shares)	0.0
Exercised (in shares)	(0.4)
Outstanding at December 31, 2016 (in shares)	1.3	1.3
Vested and exercisable at December 31, 2016 (in shares)	0.5
Per Share Weighted- Average Exercise Price
Outstanding at December 31, 2015 (in Dollars per share)	$ 56.47
Granted (in Dollars per share)	80.06
Exercised (in Dollars per share)	40.65
Outstanding at December 31, 2016 (in Dollars per share)	66.22	$ 56.47
Vested and exercisable at December 31, 2016 (in Dollars per share)	55.15
Per Share Weighted- Average Grant Date Fair Value
Outstanding at December 31, 2015 (in Dollars per share)	14.92
Granted (in Dollars per share)	16.50
Exercised (in Dollars per share)	13.03
Outstanding at December 31, 2016 (in Dollars per share)	15.77	$ 14.92
Vested and exercisable at December 31, 2016 (in Dollars per share)	$ 14.91
Weighted-Average Remaining Contractual Term (in years)
Outstanding at December 31, 2015	4 years 4 months 24 days	4 years 5 months 16 days
Granted	6 years 1 month 10 days
Outstanding at December 31, 2016	4 years 4 months 24 days	4 years 5 months 16 days
Vested and exercisable at December 31, 2016	3 years 3 months
Unvested | Stock Appreciation Rights (SARs)
SARs
Outstanding at December 31, 2016 (in shares)	0.8