Long-Term Debt (Schedule of Long-term Debt Instruments and Interest Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Long-term debt outstanding	$ 713,859		$ 713,859		$ 539,782
Interest Expense, Long-term Debt [Abstract]
Contractual interest expense	5,865	$ 4,887	11,741	$ 9,775
Amortization of debt issuance costs	804	686	1,601	1,356
Accretion of debt discount		7,016		13,877
Total interest expense	6,669	12,589	13,342	25,008
Convertible Debt [Member]
Unamortized debt issuance costs	(11,300)		(11,300)		(10,300)
2026 Convertible Secured Notes
Long-term debt, gross	500,000		500,000		500,000
Unamortized debt issuance costs	(8,930)		(8,930)		(7,132)
Unamortized debt discount	0		0		(141,303)
Long-term Debt, Total	491,070		491,070		351,565
Equity component, net of issuance costs	0		0		147,458
Interest Expense, Long-term Debt [Abstract]
Contractual interest expense	4,375		8,750
Amortization of debt issuance costs	569		1,132
Total interest expense	4,944		9,882
2026 Convertible Notes
Long-term debt, gross	115,349		115,349		115,349
Unamortized debt issuance costs	(1,895)		(1,895)		(2,313)
Unamortized debt discount					(30,228)
Long-term Debt, Total	113,454		113,454		82,808
Equity component, net of issuance costs					62,841
Interest Expense, Long-term Debt [Abstract]
Contractual interest expense	577	1,150	1,154	2,300
Amortization of debt issuance costs	116	196	232	386
Accretion of debt discount		2,553		5,043
Total interest expense	693	3,899	1,386	7,729
2023 Convertible Notes
Long-term debt, gross	109,808		109,808		113,655
Unamortized debt issuance costs	(473)		(473)		(816)
Unamortized debt discount					(7,430)
Long-term Debt, Total	109,335		109,335		105,409
Equity component, net of issuance costs					$ 97,072
Interest Expense, Long-term Debt [Abstract]
Contractual interest expense	913	3,737	1,837	7,475
Amortization of debt issuance costs	119	490	237	970
Accretion of debt discount		4,463		8,834
Total interest expense	$ 1,032	$ 8,690	$ 2,074	$ 17,279