Business and Nature of Operations - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			12 Months Ended
	Dec. 31, 2019	Jan. 31, 2019	Nov. 30, 2017	Dec. 31, 2019	Dec. 31, 2018
0.125% Convertible Senior Notes Due 2024
Business And Nature Of Operations [Line Items]
Aggregate principal amount	$ 450,000			$ 450,000
Debt instrument, interest rate	0.125%			0.125%
Debt instrument, maturity date	Dec. 15, 2024
Cost of purchased capped call options	$ 44,900
1.50% Convertible Senior Notes Due 2022 Repurchase
Business And Nature Of Operations [Line Items]
Repayments of debt				$ 57,800
Repurchase of aggregate principal amount	23,000			23,000
Partially terminated capped call options				5,800
1.50% Convertible Senior Notes Due 2022
Business And Nature Of Operations [Line Items]
Aggregate principal amount	$ 92,000		$ 115,000	$ 92,000	$ 115,000
Debt instrument, interest rate	1.50%		1.50%	1.50%
Debt instrument, maturity date			Nov. 01, 2022
Cost of purchased capped call options			$ 12,900
Follow-On Public Offering
Business And Nature Of Operations [Line Items]
Issuance of common stock, public offering, net of issuance costs, shares		2,645,000
Issuance of common stock, public offering, price per share		$ 55.25
Proceeds from issuance of common stock		$ 139,100
Underwriter Purchase Option [Member]
Business And Nature Of Operations [Line Items]
Issuance of common stock, public offering, net of issuance costs, shares		345,000
Underwriter Purchase Option [Member] | 0.125% Convertible Senior Notes Due 2024
Business And Nature Of Operations [Line Items]
Aggregate principal amount	$ 75,000			$ 75,000
Underwriter Purchase Option [Member] | 1.50% Convertible Senior Notes Due 2022
Business And Nature Of Operations [Line Items]
Aggregate principal amount			$ 15,000