Convertible Senior Notes - Narrative (Details)		3 Months Ended		9 Months Ended
	Apr. 15, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($) trading_day	Sep. 30, 2019 USD ($) business_day
Debt Instrument [Line Items]
Implied estimated effective rate	10.24%
Induced conversion of convertible debt expense		$ 700,000		$ 1,300,000
Issuance cost, equity component			$ 1,100,000
Description of event of default, default on payment of interest period	30 days
Description of event of default, aggregate principal amount of final judgments	$ 10,000,000
Description of event of default, final judgment payment period	60 days
Percentage of principal amount due if event of default occurs (at least)	25.00%
Income tax benefit, equity transaction		4,100,000	$ 4,100,000	4,100,000
Convertible Notes
Debt Instrument [Line Items]
Debt issued		80,000,000		80,000,000	$ 80,000,000	$ 80,000,000	$ 80,000,000
Equity component of notes		17,624,000		17,624,000	17,624,000	17,624,000	17,624,000
Issuance cost, equity component		1,094,000		1,094,000	$ 1,094,000	$ 1,094,000	$ 1,094,000
Convertible Senior Notes due 2024 | Convertible Notes
Debt Instrument [Line Items]
Debt issued	$ 80,000,000.0
Stated interest rate	4.50%
Conversion rate	0.0350217
Convertible debt, threshold, trading days | trading_day						20
Convertible debt, threshold, consecutive trading days | trading_day						30
Convertible debt, threshold percentage					130.00%
Convertible debt, measurement period						5	5
Convertible debt, measurement period percentage					98.00%
Liability, debt	$ 62,400,000
Equity component of notes	$ 17,600,000
Issuance costs		4,900,000		4,900,000	$ 4,900,000	$ 4,900,000	$ 4,900,000
Issuance cost, equity component		1,100,000		1,100,000	1,100,000	1,100,000	1,100,000
Issuance cost, debt		$ 3,800,000		$ 3,800,000	$ 3,800,000	$ 3,800,000	$ 3,800,000