Share-based Compensation Plans - Schedule of Stock Option Activity (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding at the beginning of the period (in shares)	1,924,179
Granted	286,750
Exercised	(366,958)
Forfeited	(316,135)
Outstanding at the end of the period (in shares)	1,527,836
Vested and expected to vest	1,437,703
Options exercisable (in shares)	936,561
Outstanding at the beginning of the period (in dollars per share)	$ 33.12
Granted	$ 33.20
Exercised	$ 26.05
Forfeited	$ 32.78
Outstanding at the end of the period (in dollars per share)	$ 34.91
Vested and expected to vest	$ 35.23
Options exercisable	$ 36.64
Options outstanding, weighted average remaining contractual term	4 years 5 months 23 days
Options vested and expected, weighted average remaining contractual term	4 years 2 months 19 days
Options exercisable, weighted average remaining contractual term	2 years 8 months 19 days