Stock-Based Compensation - Summary of Information on Options Granted Under Executive Incentive Plan (Detail) (USD $)	3 Months Ended
Mar. 31, 2013
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Lower Limit	$ 13.12
Exercise Price, Upper Limit	$ 84.80
Outstanding Number of Options	2,926,541
Average Remaining Contractual Life (years)	8 years 7 months 6 days
Outstanding Weighted Average Exercise Price	$ 27.42
Exercisable Number of Options	894,906
Exercisable Weighted Average Exercise Price	$ 30.44
Range One [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 13.12
Outstanding Number of Options	185,970
Average Remaining Contractual Life (years)	3 years 8 months 9 days
Outstanding Weighted Average Exercise Price	$ 13.12
Exercisable Number of Options	185,970
Exercisable Weighted Average Exercise Price	$ 13.12
Range Two [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 25.36
Outstanding Number of Options	69,373
Average Remaining Contractual Life (years)	9 years 9 months 29 days
Outstanding Weighted Average Exercise Price	$ 25.36
Exercisable Number of Options
Exercisable Weighted Average Exercise Price
Range Three [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 25.52
Outstanding Number of Options	1,934,942
Average Remaining Contractual Life (years)	8 years 11 months 27 days
Outstanding Weighted Average Exercise Price	$ 25.52
Exercisable Number of Options
Exercisable Weighted Average Exercise Price
Range Four [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 28.88
Outstanding Number of Options	24,686
Average Remaining Contractual Life (years)	5 years 9 months
Outstanding Weighted Average Exercise Price	$ 28.88
Exercisable Number of Options	19,750
Exercisable Weighted Average Exercise Price	$ 28.88
Range Five [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 33.52
Outstanding Number of Options	647,911
Average Remaining Contractual Life (years)	8 years 11 months 27 days
Outstanding Weighted Average Exercise Price	$ 33.52
Exercisable Number of Options	647,911
Exercisable Weighted Average Exercise Price	$ 33.52
Range Six [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 50.88
Outstanding Number of Options	25,625
Average Remaining Contractual Life (years)	4 years 9 months 29 days
Outstanding Weighted Average Exercise Price	$ 50.88
Exercisable Number of Options	25,625
Exercisable Weighted Average Exercise Price	$ 50.88
Range Seven [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 72.32
Outstanding Number of Options	23,224
Average Remaining Contractual Life (years)	7 years 29 days
Outstanding Weighted Average Exercise Price	$ 72.32
Exercisable Number of Options	9,650
Exercisable Weighted Average Exercise Price	$ 72.32
Range Eight [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 84.80
Outstanding Number of Options	14,810
Average Remaining Contractual Life (years)	7 years 9 months 29 days
Outstanding Weighted Average Exercise Price	$ 84.80
Exercisable Number of Options	6,000
Exercisable Weighted Average Exercise Price	$ 84.80

Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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The number of exercisable share options (fully vested and expected to vest) that may be converted as of the balance sheet date.

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As of the balance sheet date, the weighted-average exercise price (at which grantees can acquire the shares reserved for issuance) for exercisable stock options that are fully vested or expected to vest.

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The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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