Stock Options Outstanding and Exercisable Price Range Status (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding, Shares	4,340
Options Exercisable, Shares	2,496
Exercise Price Range 1
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price Range, minimum	$ 19.00
Exercise Price Range, maximum	$ 29.19
Options Outstanding, Shares	901
Options Outstanding, Weighted-Average Exercise Price	$ 27.06
Options Outstanding, Weighted-Average Remaining Contractual Term (Years)	2 years 3 months 18 days
Options Exercisable, Shares	811
Options Exercisable, Weighted-Average Exercise Price	$ 26.92
Exercise Price Range 2
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price Range, minimum	$ 29.75
Exercise Price Range, maximum	$ 34.62
Options Outstanding, Shares	908
Options Outstanding, Weighted-Average Exercise Price	$ 32.28
Options Outstanding, Weighted-Average Remaining Contractual Term (Years)	8 years 2 months 12 days
Options Exercisable, Shares	147
Options Exercisable, Weighted-Average Exercise Price	$ 33.22
Exercise Price Range 3
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price Range, minimum	$ 35.18
Exercise Price Range, maximum	$ 37.83
Options Outstanding, Shares	919
Options Outstanding, Weighted-Average Exercise Price	$ 36.73
Options Outstanding, Weighted-Average Remaining Contractual Term (Years)	6 years 7 months 6 days
Options Exercisable, Shares	329
Options Exercisable, Weighted-Average Exercise Price	$ 36.81
Exercise Price Range 4
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price Range, minimum	$ 37.95
Exercise Price Range, maximum	$ 43.27
Options Outstanding, Shares	913
Options Outstanding, Weighted-Average Exercise Price	$ 40.61
Options Outstanding, Weighted-Average Remaining Contractual Term (Years)	5 years 10 months 24 days
Options Exercisable, Shares	533
Options Exercisable, Weighted-Average Exercise Price	$ 40.53
Exercise Price Range 5
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price Range, minimum	$ 44.47
Exercise Price Range, maximum	$ 70.55
Options Outstanding, Shares	699
Options Outstanding, Weighted-Average Exercise Price	$ 57.99
Options Outstanding, Weighted-Average Remaining Contractual Term (Years)	3 years 2 months 12 days
Options Exercisable, Shares	676
Options Exercisable, Weighted-Average Exercise Price	$ 58.13