Credit Facilities - Narrative (Details)					3 Months Ended
	Mar. 31, 2019 USD ($)	Aug. 09, 2018 USD ($) shares	Jan. 05, 2018 USD ($)	Nov. 02, 2015 USD ($) $ / shares	Mar. 31, 2019 USD ($) day	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Nov. 20, 2018 USD ($)	Apr. 03, 2017 USD ($)	Dec. 10, 2013
Debt Instrument [Line Items]
Outstanding borrowings relating to revolving loan facility	$ 0				$ 0		$ 0
Long-term debt	252,365,000				252,365,000
Payable in kind interest expense on term loan facility					1,943,000	$ 0
Change in fair value of derivative liabilities					(2,023,000)	0
Cash paid for debt extinguishment					0	1,310,000
Loss on debt extinguishment					0	$ 2,270,000
Commitment fee amount		$ 500,000
Other debt	4,281,000				4,281,000		$ 4,281,000
Convertible Senior Notes Due 2020
Debt Instrument [Line Items]
Debt instrument, face amount	$ 40,500,000.0				$ 40,500,000.0
Debt instrument, stated interest rate	3.25%				3.25%
Credit Agreement
Debt Instrument [Line Items]
Debt instrument, face amount		50,000,000
Global liquidity requirement					$ 22,500,000
Remaining borrowing capacity	$ 22,100,000				22,100,000
Term loan facility
Debt Instrument [Line Items]
Long-term debt	163,584,000				163,584,000
Term loan facility | Facility Agreement, Due 2023
Debt Instrument [Line Items]
Debt instrument, face amount									$ 120,000,000.0
Deferred financing costs	4,000,000				4,000,000				5,100,000
Long-term debt	122,200,000				122,200,000
Term loan facility | Amended Facility Agreement
Debt Instrument [Line Items]
Payable in kind interest expense on term loan facility					3,100,000
Term Loan | Credit Agreement
Debt Instrument [Line Items]
Debt instrument, face amount	160,500,000.0				160,500,000.0
Outstanding borrowings relating to revolving loan facility	113,100,000				113,100,000
Debt discount	47,400,000				47,400,000
Convertible senior notes
Debt Instrument [Line Items]
Long-term debt	84,500,000				84,500,000
Convertible senior notes | Convertible Senior Notes Due 2020
Debt Instrument [Line Items]
Debt instrument, face amount				$ 125,000,000
Debt instrument, stated interest rate				3.25%
Debt discount				$ 2,900,000
Deferred financing costs, gross	700,000				$ 700,000
Convertible, threshold consecutive trading days | day					30
Holding threshold to declare debt due					25.00%
Convertible debt, conversion ratio				8.9431
Conversion price | $ / shares				$ 111.82
Redemption price					100.00%
Fair value disclosure				$ 97,800,000
Beneficial conversion feature				27,200,000
Convertible notes payable	77,700,000				$ 77,700,000
Periodic payment, principal					0
Convertible senior notes | Convertible Senior Notes due 2018
Debt Instrument [Line Items]
Debt instrument, stated interest rate										2.25%
Other notes payable
Debt Instrument [Line Items]
Long-term debt	4,281,000				4,281,000
Minimum | Term loan facility | Facility Agreement, Due 2023
Debt Instrument [Line Items]
Periodic interest payment					4,200,000
Minimum | Convertible senior notes | Convertible Senior Notes Due 2020
Debt Instrument [Line Items]
Periodic interest payment					6,400,000
Maximum | Term loan facility | Facility Agreement, Due 2023
Debt Instrument [Line Items]
Periodic interest payment					31,000,000
Maximum | Convertible senior notes | Convertible Senior Notes Due 2020
Debt Instrument [Line Items]
Periodic interest payment					$ 7,200,000
Facility Agreement, Due 2023, Deerfield Warrants | Facility Agreement, Due 2023
Debt Instrument [Line Items]
Expiration date for warrants					7 years
Percentage of common stock limiting exercise of warrants					4.985%
Derivative liabilities | 2018 Deerfield Warrants
Debt Instrument [Line Items]
Derivative liabilities		16,400,000
Other assets | Convertible senior notes | Convertible Senior Notes Due 2020
Debt Instrument [Line Items]
Debt discount				3,700,000
Additional Paid-In Capital | Convertible senior notes | Convertible Senior Notes Due 2020
Debt Instrument [Line Items]
Debt discount				$ 800,000
Japan Lifeline Co., Ltd.
Debt Instrument [Line Items]
Other debt								$ 4,300,000
Japan Lifeline Co., Ltd. | Other notes payable
Debt Instrument [Line Items]
Debt instrument, stated interest rate								2.50%
Closing
Debt Instrument [Line Items]
Commitment fee amount		200,000
First Anniversary
Debt Instrument [Line Items]
Commitment fee amount		$ 200,000
Termination fee		2.50%
Second Anniversary
Debt Instrument [Line Items]
Commitment fee amount		$ 100,000
Termination fee		1.50%
Expiration
Debt Instrument [Line Items]
Commitment fee amount		$ 1,000,000
Third Anniversary
Debt Instrument [Line Items]
Termination fee		0.50%
Thereafter, Fee
Debt Instrument [Line Items]
Termination fee		0.00%
Revolving loan facility
Debt Instrument [Line Items]
Deferred financing costs	600,000				$ 600,000
Debt instrument, stated interest rate		5.50%
Revolving credit facility, maximum borrowing capacity		$ 24,000,000
Revolving loan facility | Amended and Restated Facility Agreement
Debt Instrument [Line Items]
Debt instrument, face amount		$ 40,500,000.0
Debt instrument, stated interest rate		5.00%
Interest rate, payable in kind		4.75%
Maximum shares issuable to satisfy obligation to pay interest owed | shares		252,680
Maximum number of shares under mandatory redemption | shares		1,430,001
Principal amount of loan converted into stock to credit first against principal and payable in kind interest due 2021		$ 60,000,000
Termination fee payable		6,100,000
Revolving loan facility | Deerfield ELGX Revolver, LLC
Debt Instrument [Line Items]
Debt instrument, face amount	120,000,000				$ 120,000,000
Global liquidity requirement	$ 17,500,000.0	$ 22,500,000.0
Deferred financing costs, gross									1,200,000
Revolving credit facility, maximum borrowing capacity									50,000,000
Cash paid for debt extinguishment			$ 1,300,000
Write off of deferred debt issuance cost			1,000,000
Loss on debt extinguishment			$ 2,300,000
Debt Instrument, Redemption, Period One | Convertible senior notes | Convertible Senior Notes Due 2020
Debt Instrument [Line Items]
Threshold trading days | day					30
Debt Instrument, Redemption, Period Two | Convertible senior notes | Convertible Senior Notes Due 2020
Debt Instrument [Line Items]
Threshold trading days | day					2
Convertible Condition One | Convertible senior notes | Convertible Senior Notes Due 2020
Debt Instrument [Line Items]
Threshold trading days | day					20
Convertible, threshold consecutive trading days | day					30
Convertible, threshold percentage of stock price trigger					130.00%
Convertible Condition Two | Convertible senior notes | Convertible Senior Notes Due 2020
Debt Instrument [Line Items]
Convertible, threshold percentage of stock price trigger					98.00%
Convertible, threshold business days					5 days
Convertible, threshold consecutive business days					5 days
Convertible Condition Three | Convertible senior notes | Convertible Senior Notes Due 2020
Debt Instrument [Line Items]
Threshold trading days | day					2
Common Stock | Facility Agreement, Due 2023, Deerfield Warrants | Facility Agreement, Due 2023
Debt Instrument [Line Items]
Fair value of warrants									14,300,000
Deferred financing costs, gross									400,000
Common Stock | 2018 Deerfield Warrants | Facility Agreement, Due 2023
Debt Instrument [Line Items]
Fair value of warrants									10,300,000
Deferred financing costs, gross									$ 100,000
London Interbank Offered Rate (LIBOR) | Revolving loan facility
Debt Instrument [Line Items]
Variable rate		1.00%
Minimum amount, interest accrued		$ 9,750,000