Stock-Based Compensation - Stock Options by Exercise Price (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Shares Underlying Outstanding Options (in shares)	13,654
Weighted- Average Remaining Contractual Life (Years)	8 years 3 months 18 days
Weighted- Average Exercise Price per Share (in dollars per share)	$ 17.63
Number of Shares Underlying Outstanding Options (in shares)	3,397
Weighted- Average Exercise Price per Share (in dollars per share)	$ 5.36
$3.33
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	$ 3.33
Exercise price range, maximum (in dollars per share)	$ 3.33
Number of Shares Underlying Outstanding Options (in shares)	2,116
Weighted- Average Remaining Contractual Life (Years)	6 years 9 months 18 days
Weighted- Average Exercise Price per Share (in dollars per share)	$ 3.33
Number of Shares Underlying Outstanding Options (in shares)	1,457
Weighted- Average Exercise Price per Share (in dollars per share)	$ 3.33
$4.16 - $4.18
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	$ 4.18
Exercise price range, maximum (in dollars per share)	$ 4.16
Number of Shares Underlying Outstanding Options (in shares)	2,272
Weighted- Average Remaining Contractual Life (Years)	7 years 7 months 6 days
Weighted- Average Exercise Price per Share (in dollars per share)	$ 4.17
Number of Shares Underlying Outstanding Options (in shares)	875
Weighted- Average Exercise Price per Share (in dollars per share)	$ 4.17
$4.92 - $7.76
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	$ 7.76
Exercise price range, maximum (in dollars per share)	$ 4.92
Number of Shares Underlying Outstanding Options (in shares)	1,868
Weighted- Average Remaining Contractual Life (Years)	8 years
Weighted- Average Exercise Price per Share (in dollars per share)	$ 6.30
Number of Shares Underlying Outstanding Options (in shares)	618
Weighted- Average Exercise Price per Share (in dollars per share)	$ 5.81
$8.77 - $10.18
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	$ 10.18
Exercise price range, maximum (in dollars per share)	$ 8.77
Number of Shares Underlying Outstanding Options (in shares)	2,624
Weighted- Average Remaining Contractual Life (Years)	8 years 7 months 6 days
Weighted- Average Exercise Price per Share (in dollars per share)	$ 9.73
Number of Shares Underlying Outstanding Options (in shares)	313
Weighted- Average Exercise Price per Share (in dollars per share)	$ 9.50
$22.49 -$30.67
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	$ 30.67
Exercise price range, maximum (in dollars per share)	$ 22.49
Number of Shares Underlying Outstanding Options (in shares)	2,652
Weighted- Average Remaining Contractual Life (Years)	9 years 1 month 6 days
Weighted- Average Exercise Price per Share (in dollars per share)	$ 27.58
Number of Shares Underlying Outstanding Options (in shares)	127
Weighted- Average Exercise Price per Share (in dollars per share)	$ 22.59
$34.12 - $68.34
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	$ 68.34
Exercise price range, maximum (in dollars per share)	$ 34.12
Number of Shares Underlying Outstanding Options (in shares)	1,888
Weighted- Average Remaining Contractual Life (Years)	9 years 7 months 6 days
Weighted- Average Exercise Price per Share (in dollars per share)	$ 50.84
Number of Shares Underlying Outstanding Options (in shares)	7
Weighted- Average Exercise Price per Share (in dollars per share)	$ 36.38
$75.00 - $76.80
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	$ 76.80
Exercise price range, maximum (in dollars per share)	$ 75.00
Number of Shares Underlying Outstanding Options (in shares)	224
Weighted- Average Remaining Contractual Life (Years)	9 years 8 months 12 days
Weighted- Average Exercise Price per Share (in dollars per share)	$ 75.71
Number of Shares Underlying Outstanding Options (in shares)	0
Weighted- Average Exercise Price per Share (in dollars per share)	$ 0.00
$84.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, minimum (in dollars per share)	$ 84.00
Exercise price range, maximum (in dollars per share)	$ 84.00
Number of Shares Underlying Outstanding Options (in shares)	10
Weighted- Average Remaining Contractual Life (Years)	9 years 8 months 12 days
Weighted- Average Exercise Price per Share (in dollars per share)	$ 84.00
Number of Shares Underlying Outstanding Options (in shares)	0
Weighted- Average Exercise Price per Share (in dollars per share)	$ 0.00

Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(iii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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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

-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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The number of shares reserved for issuance pertaining to the outstanding exercisable stock options as of the balance sheet date in the customized range of exercise prices for which the market and performance vesting condition has been satisfied.

+ 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 (c)(iii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices.

+ 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 (c)(1)(i)-(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices.

+ 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 (c)(1)(i)-(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Weighted average remaining contractual term of outstanding stock options, 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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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)

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