Stock-Based Compensation Plans - Summary of Stock Option Activity Under All Plans (Detail) - Stock Options [Member] - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding, beginning of period, Shares	148	539	685
Granted, Shares	28	35	29
Exercised, Shares	(43)	(426)	(174)
Forfeited, Shares			(1)
Options outstanding, end of period, Shares	133	148	539
Options exercisable, end of period, Shares	72	86	486
Options vested and expected to vest, end of period, Shares	130	145	536
Weighted average fair value of options granted during the period	$ 19.49	$ 15.21	$ 17.26
Options outstanding, beginning of period, Exercise Price	46	36	34
Granted, Exercise Price	60	47	50
Exercised, Exercise Price	47	33	29
Forfeited, Exercise Price			50
Options outstanding, end of period, Exercise Price	49	46	36
Options exercisable, end of period, Exercise Price	46	46	35
Options vested and expected to vest, end of period, Exercise Price	$ 49	$ 46	$ 36