Long-Term Debt (Details) $ / shares in Units, $ in Thousands				1 Months Ended			3 Months Ended		6 Months Ended		27 Months Ended	37 Months Ended
	Jul. 15, 2014 $ / shares shares	Jun. 30, 2014 $ / shares $ / item	Jan. 31, 2013 USD ($) item $ / shares $ / item shares	Aug. 31, 2016 USD ($)	May 31, 2016 USD ($)	Jan. 31, 2013 USD ($) item $ / shares $ / item	Jun. 30, 2016 USD ($) $ / shares $ / item	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) $ / shares $ / item	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) $ / shares $ / item	Apr. 17, 2017	Dec. 31, 2015 USD ($)	Apr. 30, 2014 USD ($)
Debt disclosures
Total long-term debt							$ 739,126		$ 739,126		$ 739,126		$ 748,271
Unamortized debt issuance costs							(13,573)		(13,573)		(13,573)		(15,140)
Current portion of long-term debt							(3,266)		(3,266)		(3,266)		0
Net long-term debt							722,287		722,287		722,287		733,131
Settlement amount for purchase of notes									8,095	$ 0
Amount received from capped call option									391	0
Interest amount added to principal balance									855	12,836
Convertible Subordinated Notes Due 2023
Debt disclosures
Convertible Subordinated Notes due 2023							$ 245,109		$ 245,109		$ 245,109		255,109
Total long-term debt					$ 9,800
Loan amount			$ 287,500		10,000	$ 287,500
Proceeds from issuances of note payable, net of debt issuance costs			$ 281,200
Interest rate (as a percent)			2.125%			2.125%
Conversion rate of shares		46.9087				35.9903			50.5818
Conversion price of convertible notes into common stock (in dollars per share) | $ / shares		$ 21.32	$ 27.79			$ 27.79	$ 19.77		$ 19.77		$ 19.77
Percentage of principal amount at which the entity may be forced to redeem some or all notes as a result of a fundamental change (as defined)			100.00%
Settlement amount for purchase of notes					8,100
Convertible Subordinated Notes Due 2023 | Other income (expense)
Debt disclosures
Gain on repurchase of notes					$ 1,700
Convertible Subordinated Notes Due 2023 | Common Stock
Debt disclosures
Conversion price of convertible notes into common stock (in dollars per share) | $ / shares	$ 21.32
Debt Conversion, Converted Instrument, Shares Issued | shares	1,519,402
Number of common stares received | shares	149,645
Convertible Subordinated Notes Due 2023 | Privately-negotiated capped call option
Debt disclosures
Payments for capped call options			$ 36,800
Number of derivative instruments purchased | item			2			2
Strike price for the underlying number of shares (in dollars per share) | $ / shares		$ 21.32	$ 27.79						$ 19.77
Cap price for the underlying number of shares (in dollars per share) | $ / item		29.16	38.00			38.00	27.04		27.04		27.04
Amount received from capped call option									$ 400
Convertible Subordinated Notes Due 2023 | Stock prices below $27.79 per share | Maximum
Debt disclosures
Net shares settlement payable to the entity | shares			2,779,659
Convertible Subordinated Notes Due 2023 | Stock prices below $27.79 per share | Minimum
Debt disclosures
Net shares settlement payable to the entity | shares			0
Convertible Subordinated Notes Due 2023 | Stock prices above $38.00 per share
Debt disclosures
Incremental Common Shares Attributable to Capped Call Options | shares			0
9% fixed rate term notes due 2029
Debt disclosures
Non-Recourse Notes Payable due 2029							$ 494,017		494,017		$ 494,017		$ 493,162
9% fixed rate term notes due 2029 | GSK
Debt disclosures
Loan amount							494,000		494,000		494,000			$ 450,000
Interest rate (as a percent)														9.00%
Interest amount added to principal balance							$ 200	$ 6,400	$ 900	$ 12,800	$ 44,000
9% fixed rate term notes due 2029 | Future
Debt disclosures
Debt prepayment premium (as a percent)												2.50%
9% fixed rate term notes due 2029 | Future | GSK
Debt disclosures
Periodical interest payment				$ 3,300