Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

The following tables set forth the fair value of the Company’s financial instruments (in millions):

	As of December 31, 2017
			Fair Value Measurements Using
	Carrying Amount		Quoted Price in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value
Financial liabilities:
Senior convertible notes (2021 notes)	$	24.4	$	—	$	—	$	19.8	$	19.8
Facility financing obligation		52.7		—		—		54.6		54.6
Milestone rights		8.9		—		—		19.1		19.1
Total financial liabilities	$	86.0	$	—	$	—	$	93.5	$	93.5

	As of December 31, 2016
			Fair Value Measurements Using
	Carrying Value		Quoted Price in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value
Financial liabilities:
Senior convertible notes (2018 notes)	$	27.6	$	—	$	—	$	22.9	$	22.9
Facility financing obligation		71.3		—		—		74.5		74.5
Milestone rights		8.9		—		—		18.4		18.4
Warrant liability (at recurring fair value)		7.4		—		—		7.4		7.4
Total financial liabilities	$	115.2	$	—	$	—	$	123.2	$	123.2

Fair Values of Financial Liabilities which Include Level 3 Instruments

The following table provides a roll forward of the fair values of financial assets and liabilities that are carried at fair value (in millions):

	Warrants			Assets Held for Sale
Fair value, January 1, 2016	$	—		$	—
Additions		12.8			17.3
Changes in fair value		(5.4	)		(0.6	)
Payments		—			—
Fair value, December 31, 2016	$	7.4		$	16.7
Additions		—			—
Changes in fair value		(5.5	)		—
Settlement through exchange of common shares		(1.9	)
Payments		—			(16.7	)
Fair value, December 31, 2017	$	—		$	—