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Stock-Based Compensation - Options by exercise price (Details)	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Stock options outstanding and exercisable by exercise price
Stock Options Outstanding, Number of Shares | shares	3,370,901
Stock Options Outstanding, Remaining Contractual Term	6 years 11 months 23 days
Stock Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 8.50
Stock Options Exercisable, Number of Shares | shares	1,600,351
Stock Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 3.99
$0.59 - $4.25
Stock options outstanding and exercisable by exercise price
Range of Exercise Prices, lower limit (in dollars per share)	0.59
Range of Exercise Prices, upper limit (in dollars per share)	$ 4.25
Stock Options Outstanding, Number of Shares | shares	1,413,261
Stock Options Outstanding, Remaining Contractual Term	4 years 7 months 6 days
Stock Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 1.87
Stock Options Exercisable, Number of Shares | shares	1,163,519
Stock Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 1.38
$5.50 - $8.56
Stock options outstanding and exercisable by exercise price
Range of Exercise Prices, lower limit (in dollars per share)	5.50
Range of Exercise Prices, upper limit (in dollars per share)	$ 8.56
Stock Options Outstanding, Number of Shares | shares	50,000
Stock Options Outstanding, Remaining Contractual Term	7 years 7 months 2 days
Stock Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 7.64
Stock Options Exercisable, Number of Shares | shares	20,808
Stock Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 7.09
$9.26 – $14.38
Stock options outstanding and exercisable by exercise price
Range of Exercise Prices, lower limit (in dollars per share)	9.26
Range of Exercise Prices, upper limit (in dollars per share)	$ 14.38
Stock Options Outstanding, Number of Shares | shares	1,026,140
Stock Options Outstanding, Remaining Contractual Term	8 years 3 months 29 days
Stock Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 11.20
Stock Options Exercisable, Number of Shares | shares	415,899
Stock Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 11.11
$14.54 – $22.35
Stock options outstanding and exercisable by exercise price
Range of Exercise Prices, lower limit (in dollars per share)	14.54
Range of Exercise Prices, upper limit (in dollars per share)	$ 22.35
Stock Options Outstanding, Number of Shares | shares	881,500
Stock Options Outstanding, Remaining Contractual Term	9 years 2 months 5 days
Stock Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 16.00
Stock Options Exercisable, Number of Shares | shares	125
Stock Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 16.52

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No definition available.

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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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- Definition

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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- Definition

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 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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- Definition

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

+ 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)(iii)
-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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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
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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