Long-term Debt - 2.25% Convertible Senior Notes (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2020 USD ($) d $ / shares	Mar. 31, 2019 USD ($)	Dec. 31, 2018	Dec. 31, 2019 USD ($) $ / shares	Dec. 14, 2016 USD ($)
Debt Instrument [Line Items]
Current portion of long-term debt	$ 289,000,000.0			$ 284,700,000
Carrying value	$ 623,800,000			628,100,000
Share price (in USD per share) | $ / shares	$ 41.83
Interest expense components for 2 1/4% Notes
Interest expense-contractual interest	$ 1,700,000	$ 1,700,000
Interest expense-amortization of debt discount	1,900,000	1,800,000
Interest expense-amortization of deferred financing costs	200,000	$ 200,000
2 1/4% Notes
Debt Instrument [Line Items]
Carrying value	$ 300,000,000.0			$ 300,000,000.0
Convertible Debt | 2 1/4% Notes
Debt Instrument [Line Items]
Principal amount					$ 300,000,000.0
Debt convertible trigger stock price (in USD per share) | $ / shares	$ 33.80
Debt convertible threshold trading days | d	20
Debt convertible threshold consecutive trading days | d	30
Current portion of long-term debt	$ 265,100,000
Convertible debt threshold percentage of stock price trigger	130.00%
Effective interest rate (as a percent)	5.80%			5.80%
Carrying value	$ 265,100,000			$ 263,000,000.0
Unamortized discount and deferred financing costs	34,900,000			37,000,000.0
Principal amount	300,000,000.0			300,000,000.0
Carrying amount of equity component, net of equity issuance costs	$ 54,500,000			$ 54,500,000
Remaining amortization period (years)	3 years 9 months		4 years
Conversion rate (shares of common stock per $1,000 principal amount)	38.4615		38.4615
Conversion price (in USD per share) | $ / shares	$ 26.00			$ 26.00
Debt Component of Convertible Debt | 2 1/4% Notes
Debt Instrument [Line Items]
If-converted value in excess of principal	$ 182,600,000