Stock-Based Compensation Plans - Summary of Stock Option Activity Under All Plans (Detail) - Stock Options [Member] - $ / shares shares in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 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	(38)	(201)
Options outstanding, end of period, Shares	138	373
Options exercisable, end of period, Shares	77	311
Options vested and expected to vest, end of period, Shares	135	371
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	48	34
Options outstanding, end of period, Exercise Price	49	38
Options exercisable, end of period, Exercise Price	45	36
Options vested and expected to vest, end of period, Exercise Price	$ 49	$ 38