Fair Value Measurements (Summary of Valuation of Company's Financial Instruments by Various Levels) (Parenthetical) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 7,744	$ 6,858
Other non-current assets	76,350	$ 82,750
Convertible debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	172,000
Other non-current assets	$ 346,000