Stock-Based Compensation Plans - Summary of Stock Option Activity Under All Plans (Detail) (Equity Option [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Equity Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding, beginning of period, Shares	685	1,501
Granted, Shares	29	29
Exercised, Shares	(44)	(622)
Options outstanding, end of period, Shares	670	908
Options exercisable, end of period, Shares	613	840
Options vested and expected to vest, end of period, Shares	667	905
Weighted average fair value of options granted during the period	$ 17.26	$ 15.18
Options outstanding, beginning of period, Exercise Price	$ 34	$ 31
Granted, Exercise Price	$ 50	$ 44
Exercised, Exercise Price	$ 28	$ 29
Options outstanding, end of period, Exercise Price	$ 35	$ 33
Options exercisable, end of period, Exercise Price	$ 34	$ 33
Options vested and expected to vest, end of period, Exercise Price	$ 35	$ 33