Subsequent Events (Details)	Apr. 03, 2019 USD ($)	Mar. 31, 2019 USD ($) day investor $ / shares shares	Aug. 09, 2018 USD ($)	Mar. 29, 2019 $ / shares	Dec. 31, 2018 shares
Subsequent Event [Line Items]
Number of shares issued on transaction | shares		7,889,552
Sale of stock price per share (usd per share) | $ / shares				$ 6.61
Investors' ownership		19.99%
Number of investors holding notes | investor		2
New Mandatory Note
Subsequent Event [Line Items]
Debt instrument, face amount		$ 25,000,000.0
New Mandatory Note | Holders
Subsequent Event [Line Items]
Debt instrument, face amount		42,020,000.00
Convertible senior notes
Subsequent Event [Line Items]
Face value per note, converted amount received by Holders		900
Face amount of each note that is convertible		$ 1,000
Convertible senior notes | Convertible Senior Notes Issued November 2015
Subsequent Event [Line Items]
Debt instrument, stated interest rate		3.25%
Convertible senior notes | Convertible Senior Notes Issued November 2015 | Two Investors
Subsequent Event [Line Items]
Debt instrument, face amount		$ 73,400,000.0
Convertible senior notes | Convertible Senior Notes Due 2024
Subsequent Event [Line Items]
Debt instrument, stated interest rate		5.00%
Face amount of each note that is convertible		$ 1.00
Maximum Conversion Amount		30.00%
Convertible debt, conversion ratio		0.15129
Convertible debt redemption, consecutive trading days threshold | day		5
Convertible debt redemption, percentage of stock price trigger		100.00%
Mandatory conversion of shares		$ 1,666,666
Voluntary conversion amount		1,666,666
Convertible senior notes | Voluntary Conversion
Subsequent Event [Line Items]
Face amount of each note that is convertible		$ 1.00
Convertible debt, conversion ratio		0.12103
Conversion price equity offering price		125.00%
Conversion limit on shares, outstanding principal per month		30.00%
Convertible debt redemption, percentage of stock price trigger		110.00%
Revolving loan facility
Subsequent Event [Line Items]
Debt instrument, stated interest rate			5.50%
Deerfield ELGX Revolver, LLC
Subsequent Event [Line Items]
Maximum equity owned by Investor		4.985%
Stock trigger price (usd per share) | $ / shares		$ 6.625
Mandatory conversion of shares		$ 1,666,666
Voluntary conversion amount		50,000,000.0
Exit fee upon termination		5,000,000
Commitment reduction		10,000,000
Financing receivable gross		40,000,000
Deerfield ELGX Revolver, LLC | Maximum
Subsequent Event [Line Items]
Mandatory conversion of shares		$ 25,000,000.0
Deerfield ELGX Revolver, LLC | Fixed Price Conversion
Subsequent Event [Line Items]
VWAP Days | day		5
Deerfield ELGX Revolver, LLC | Voluntary Conversion
Subsequent Event [Line Items]
Volume weighted average price rate trigger		85.00%
VWAP Days | day		15
Deerfield ELGX Revolver, LLC | Optional Required Voluntary Conversion
Subsequent Event [Line Items]
Volume weighted average price rate trigger		175.00%
VWAP Days | day		15
Deerfield ELGX Revolver, LLC | Term loan facility | Second Amendment to Facility Agreement
Subsequent Event [Line Items]
Maximum number of shares under mandatory redemption | shares		1,430,000
Percentage of market value attributable to principal that is paid with common stock		96.00%
Deerfield ELGX Revolver, LLC | Revolving loan facility
Subsequent Event [Line Items]
Debt instrument, face amount		$ 120,000,000
Global liquidity requirement		$ 17,500,000.0	$ 22,500,000.0
Waterfall loans due		16.67%			33.33%
Remainder of the first out water fall loans		50.00%
Optional stock payment for interest removed | shares					250,000
Subsequent Event
Subsequent Event [Line Items]
Consideration received on transaction	$ 52,150,000
Subsequent Event | New Mandatory Note
Subsequent Event [Line Items]
Debt Instrument, Increase, Accrued Interest	67.02
Subsequent Event | New Mandatory Note | Holders
Subsequent Event [Line Items]
Proceeds from Issuance of Debt	$ 73.355