Stock-Based Compensation Plans - Summary of Stock Option Activity Under All Plans (Detail) - Stock Options [Member] - $ / shares shares in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding, beginning of period, Shares	148	539
Granted, Shares	28	35
Exercised, Shares	(43)	(296)
Options outstanding, end of period, Shares	133	278
Options exercisable, end of period, Shares	72	216
Options vested and expected to vest, end of period, Shares	130	275
Weighted average fair value of options granted during the period	$ 19.49	$ 15.21
Options outstanding, beginning of period, Exercise Price	46	36
Granted, Exercise Price	60	47
Exercised, Exercise Price	47	32
Options outstanding, end of period, Exercise Price	49	42
Options exercisable, end of period, Exercise Price	46	41
Options vested and expected to vest, end of period, Exercise Price	$ 49	$ 42