Stock Options Outstanding and Vested and Exercisable (Detail) - $ / shares	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Stock Options Outstanding, Number of Stock Options Outstanding	4,731,483	4,249,168
Outstanding	7 years 3 months 18 days
Outstanding	$ 24.19	$ 14.77
Stock Options Vested, Number of Stock Options Vested	2,341,265	2,341,265
Stock Options Vested, Weighted Average Exercise Price Per Share	$ 14.92
$3.30 - $5.10
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Lower Limit	3.30
Exercise Prices, Upper Limit	$ 5.10
Stock Options Outstanding, Number of Stock Options Outstanding	495,133
Outstanding	2 years 4 months 24 days
Outstanding	$ 4.55
Stock Options Vested, Number of Stock Options Vested	495,133
Stock Options Vested, Weighted Average Exercise Price Per Share	$ 4.55
$5.30 - $9.00
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Lower Limit	5.30
Exercise Prices, Upper Limit	$ 9.00
Stock Options Outstanding, Number of Stock Options Outstanding	767,038
Outstanding	4 years 10 months 24 days
Outstanding	$ 8.18
Stock Options Vested, Number of Stock Options Vested	743,033
Stock Options Vested, Weighted Average Exercise Price Per Share	$ 8.21
$9.50 - $22.16
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Lower Limit	9.50
Exercise Prices, Upper Limit	$ 22.16
Stock Options Outstanding, Number of Stock Options Outstanding	483,519
Outstanding	7 years 3 months 18 days
Outstanding	$ 15.29
Stock Options Vested, Number of Stock Options Vested	321,529
Stock Options Vested, Weighted Average Exercise Price Per Share	$ 14.88
$22.60-$25.00
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Lower Limit	22.60
Exercise Prices, Upper Limit	$ 25.00
Stock Options Outstanding, Number of Stock Options Outstanding	330,676
Outstanding	7 years 10 months 24 days
Outstanding	$ 23.95
Stock Options Vested, Number of Stock Options Vested	162,964
Stock Options Vested, Weighted Average Exercise Price Per Share	$ 23.95
$25.08-$25.08
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Lower Limit	25.08
Exercise Prices, Upper Limit	$ 25.08
Stock Options Outstanding, Number of Stock Options Outstanding	523,124
Outstanding	8 years
Outstanding	$ 25.08
Stock Options Vested, Number of Stock Options Vested	251,396
Stock Options Vested, Weighted Average Exercise Price Per Share	$ 25.08
$25.14-$29.19
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Lower Limit	25.14
Exercise Prices, Upper Limit	$ 29.19
Stock Options Outstanding, Number of Stock Options Outstanding	522,962
Outstanding	8 years 8 months 12 days
Outstanding	$ 27.57
Stock Options Vested, Number of Stock Options Vested	170,511
Stock Options Vested, Weighted Average Exercise Price Per Share	$ 27.83
$29.72-$29.72
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Lower Limit	29.72
Exercise Prices, Upper Limit	$ 29.72
Stock Options Outstanding, Number of Stock Options Outstanding	542,160
Outstanding	8 years 9 months 18 days
Outstanding	$ 29.72
Stock Options Vested, Number of Stock Options Vested	127,311
Stock Options Vested, Weighted Average Exercise Price Per Share	$ 29.72
$35.69-$44.39
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Lower Limit	35.69
Exercise Prices, Upper Limit	$ 44.39
Stock Options Outstanding, Number of Stock Options Outstanding	578,896
Outstanding	9 years
Outstanding	$ 40.82
Stock Options Vested, Number of Stock Options Vested	53,971
Stock Options Vested, Weighted Average Exercise Price Per Share	$ 42.84
$44.63 - $51.45
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Lower Limit	44.63
Exercise Prices, Upper Limit	$ 51.45
Stock Options Outstanding, Number of Stock Options Outstanding	479,225
Outstanding	9 years 6 months
Outstanding	$ 47.71
Stock Options Vested, Number of Stock Options Vested	14,506
Stock Options Vested, Weighted Average Exercise Price Per Share	$ 47.21
$52.74 - $52.74
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Lower Limit	52.74
Exercise Prices, Upper Limit	$ 52.74
Stock Options Outstanding, Number of Stock Options Outstanding	8,750
Outstanding	9 years 7 months 6 days
Outstanding	$ 52.74
Stock Options Vested, Number of Stock Options Vested	911
Stock Options Vested, Weighted Average Exercise Price Per Share	$ 52.74

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- Definition

Number of options outstanding, including both vested and non-vested options.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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Number of options vested.

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