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Debt - Narrative (Details)	1 Months Ended
	Jan. 31, 2018 USD ($) day $ / shares	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Debt Instrument [Line Items]
Underwriting discounts and commissions and other offering expenses | $		$ 6,345,000	$ 7,043,000
1.75 convertible senior notes due 2025
Debt Instrument [Line Items]
Initial conversion rate	0.0255384
Convertible Notes | 1.75 convertible senior notes due 2025
Debt Instrument [Line Items]
Aggregate principal amount | $	$ 450,000,000.0
Option to purchase additional debt | $	50,000,000.0
Underwriting discounts and commissions and other offering expenses | $	14,200,000
Net proceeds | $	$ 435,800,000
Initial conversion price (in dollars per share) | $ / shares	$ 39.16
Convertible Notes ($450.0 face value) | $	$ 309,100,000
Effective interest rate	7.60%
Equity component of convertible debt | $	$ 140,900,000
Remaining discount amortization period	4 years 6 months 14 days
Convertible Notes | Conversion Term (i) | 1.75 convertible senior notes due 2025
Debt Instrument [Line Items]
Threshold trading days | day	5
Threshold consecutive trading days | day	5
Threshold percent of stock price trigger	98.00%
Convertible Notes | Conversion Term (ii) | 1.75 convertible senior notes due 2025
Debt Instrument [Line Items]
Threshold trading days | day	45
Threshold consecutive trading days | day	10
Threshold percent of stock price trigger	10.00%
Convertible Notes | Conversion Term (iii) | 1.75 convertible senior notes due 2025
Debt Instrument [Line Items]
Threshold trading days following fundamental change | day	30
Convertible Notes | Conversion Term (iv) | 1.75 convertible senior notes due 2025
Debt Instrument [Line Items]
Threshold trading days | day	20
Threshold consecutive trading days | day	30
Threshold percent of stock price trigger	130.00%

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