Stock-Based Compensation Plans - Summary of Stock Option Activity Under All Plans (Detail) (Stock Options [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding, beginning of period, Shares	539	685
Granted, Shares	35	29
Exercised, Shares	(296)	(75)
Options outstanding, end of period, Shares	278	639
Options exercisable, end of period, Shares	216	587
Options vested and expected to vest, end of period, Shares	275	637
Weighted average fair value of options granted during the period	$ 15.21	$ 17.26
Options outstanding, beginning of period, Exercise Price	$ 36	$ 34
Granted, Exercise Price	$ 47	$ 50
Exercised, Exercise Price	$ 32	$ 28
Options outstanding, end of period, Exercise Price	$ 42	$ 35
Options exercisable, end of period, Exercise Price	$ 41	$ 34
Options vested and expected to vest, end of period, Exercise Price	$ 42	$ 35