Stock-Based Compensation Plans - Summary of Stock Option Activity Under All Plans (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Shares	59	52	98
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding, beginning of period, Shares	1,501	2,068	2,516
Granted, Shares	29	25	66
Exercised, Shares	(845)	(582)	(267)
Expired, Shares		(10)	(247)
Options outstanding, end of period, Shares	685	1,501	2,068
Options exercisable, end of period, Shares	617	1,348	1,834
Options vested and expected to vest, end of period, Shares	682	1,494	2,057
Weighted average fair value of options granted during the period	15.18	13.18	5.08
Options outstanding, beginning of period, Exercise Price	31	31	31
Granted, Exercise Price	44	37	18
Exercised, Exercise Price	30	30	20
Expired, Exercise Price		39	38
Options outstanding, end of period, Exercise Price	34	31	31
Options exercisable, end of period, Exercise Price	34	33	33
Options vested and expected to vest, end of period, Exercise Price	34	31	31