Commitments and Contingencies (Schedule of Supplemental Balance Sheet Information Related To Leases) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets	$ 22,671	$ 104,400	$ 113,400
Operating lease liabilities	$ 26,716	$ 115,408	$ 121,600
Weighted average remaining lease term (years)	4 years 7 months 6 days	12 years 6 months
Weighted average discount rate	5.70%	5.96%
Accrued expenses and other current liabilities [Member]
Lessee, Lease, Description [Line Items]
Operating lease liabilities	$ 9,359	$ 19,784
Operating lease liabilities, net of current portion
Lessee, Lease, Description [Line Items]
Operating lease liabilities	$ 17,357	$ 95,624