Stock-Based Compensation - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved for issuance	1,800,000
Shares of common stock available for issuance	427,781
Vesting period of stock options in years	3 years
Grant-date intrinsic value of RSU	$ 14,300,000
Weighted average remaining contractual life	1 year 1 month 6 days
Weighted-average grant-date fair value	$ 183.83	$ 188.36	$ 81.47
The total grant-date fair value of options vested	21,100,000	17,900,000	30,700,000
Cash used for employee withholding tax payments	9,100,000	7,500,000	11,500,000
Share settlement under RSUs	50,952	38,222	143,102
Compensation expense recognition period	3 years
The weighted-average remaining contractual term for stock options outstanding	3 years 10 months 24 days	4 years 9 months 18 days
The weighted-average remaining contractual term for stock options vested and exercisable	3 years 10 months 24 days
Aggregate intrinsic value of stock options outstanding	24,700,000
Aggregate intrinsic value of stock options vested and exercisable	24,700,000
The total grant-date fair value of stock options vested	400,000	200,000	1,200,000
The total intrinsic value of stock options exercised	4,200,000	5,100,000	9,200,000
Cash received from stock option exercises	753,000	570,000	2,636,000
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unamortized stock-based compensation expense	12,600,000	8,900,000
Weighted average remaining amortization periods	1 year 1 month 6 days	1 year
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual life in years	10 years
Unamortized stock-based compensation expense		100,000
Weighted average remaining amortization periods		2 months 12 days
Number of unvested stock options	0
RSU and Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company granted performance contingent RSU	27,782
Stock-based compensation expense	1,400,000
Unamortized stock-based compensation expense	$ 3,500,000
Minimum [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual life in years	1 year
Maximum [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual life in years	3 years