Fair Value Measures (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands | Sep. 30, 2020 | Dec. 31, 2019 | Sep. 30, 2019 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | $ 84,421 | $ 391,233 | $ 110,598 |
Total liabilities measured at fair value | 3,601 | 3,034 | 630 |
Level 1 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 74,027 | 304,558 | 87,308 |
Total liabilities measured at fair value | 0 | 0 | 0 |
Level 2 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 10,394 | 86,675 | 23,290 |
Total liabilities measured at fair value | 3,601 | 3,034 | 630 |
Level 3 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 0 | 0 | 0 |
Total liabilities measured at fair value | 0 | 0 | 0 |
Accrued Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total liabilities measured at fair value | 2,415 | 2,266 | 521 |
Accrued Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | Level 1 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total liabilities measured at fair value | 0 | 0 | 0 |
Accrued Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | Level 2 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total liabilities measured at fair value | 2,415 | 2,266 | 521 |
Accrued Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | Level 3 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total liabilities measured at fair value | 0 | 0 | 0 |
Other Long Term Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total liabilities measured at fair value | 1,186 | 768 | 109 |
Other Long Term Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | Level 1 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total liabilities measured at fair value | 0 | 0 | 0 |
Other Long Term Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | Level 2 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total liabilities measured at fair value | 1,186 | 768 | 109 |
Other Long Term Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | Level 3 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total liabilities measured at fair value | 0 | 0 | 0 |
Cash Equivalents [Member] | Money Market Funds [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 56,337 | | |
Cash Equivalents [Member] | Money Market Funds [Member] | Level 1 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 56,337 | | |
Cash Equivalents [Member] | Money Market Funds [Member] | Level 2 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 0 | | |
Cash Equivalents [Member] | Money Market Funds [Member] | Level 3 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 0 | | |
Cash Equivalents [Member] | US Treasury Securities [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | | 34,928 | |
Cash Equivalents [Member] | US Treasury Securities [Member] | Level 1 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | | 0 | |
Cash Equivalents [Member] | US Treasury Securities [Member] | Level 2 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | | 34,928 | |
Cash Equivalents [Member] | US Treasury Securities [Member] | Level 3 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | | 0 | |
Cash Equivalents [Member] | Commercial Paper [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | | 33,587 | |
Cash Equivalents [Member] | Commercial Paper [Member] | Level 1 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | | 0 | |
Cash Equivalents [Member] | Commercial Paper [Member] | Level 2 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | | 33,587 | |
Cash Equivalents [Member] | Commercial Paper [Member] | Level 3 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | | 0 | |
Cash and Cash Equivalents [Member] | Money Market Funds [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | | 288,926 | 72,941 |
Cash and Cash Equivalents [Member] | Money Market Funds [Member] | Level 1 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | | 288,926 | 72,941 |
Cash and Cash Equivalents [Member] | Money Market Funds [Member] | Level 2 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | | 0 | 0 |
Cash and Cash Equivalents [Member] | Money Market Funds [Member] | Level 3 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | | 0 | 0 |
Short-term Investments [Member] | Money Market Funds [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 70 | | |
Short-term Investments [Member] | Money Market Funds [Member] | Level 1 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 70 | | |
Short-term Investments [Member] | Money Market Funds [Member] | Level 2 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 0 | | |
Short-term Investments [Member] | Money Market Funds [Member] | Level 3 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 0 | | |
Short-term Investments [Member] | Mutual Fund [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 1,025 | 1,668 | 1,477 |
Short-term Investments [Member] | Mutual Fund [Member] | Level 1 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 1,025 | 1,668 | 1,477 |
Short-term Investments [Member] | Mutual Fund [Member] | Level 2 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 0 | 0 | 0 |
Short-term Investments [Member] | Mutual Fund [Member] | Level 3 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 0 | 0 | 0 |
Other Current Assets [Member] | Derivative Financial Instruments, Assets [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 6,940 | 14,001 | 18,460 |
Other Current Assets [Member] | Derivative Financial Instruments, Assets [Member] | Level 1 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 0 | 0 | 0 |
Other Current Assets [Member] | Derivative Financial Instruments, Assets [Member] | Level 2 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 6,940 | 14,001 | 18,460 |
Other Current Assets [Member] | Derivative Financial Instruments, Assets [Member] | Level 3 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 0 | 0 | 0 |
Other Noncurrent Assets [Member] | Money Market Funds [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 4,621 | 1,792 | 1,528 |
Other Noncurrent Assets [Member] | Money Market Funds [Member] | Level 1 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 4,621 | 1,792 | 1,528 |
Other Noncurrent Assets [Member] | Money Market Funds [Member] | Level 2 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 0 | 0 | 0 |
Other Noncurrent Assets [Member] | Money Market Funds [Member] | Level 3 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 0 | 0 | 0 |
Other Noncurrent Assets [Member] | Mutual Fund [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 11,974 | 12,172 | 11,362 |
Other Noncurrent Assets [Member] | Mutual Fund [Member] | Level 1 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 11,974 | 12,172 | 11,362 |
Other Noncurrent Assets [Member] | Mutual Fund [Member] | Level 2 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 0 | 0 | 0 |
Other Noncurrent Assets [Member] | Mutual Fund [Member] | Level 3 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 0 | 0 | 0 |
Other Noncurrent Assets [Member] | Derivative Financial Instruments, Assets [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 3,454 | 4,159 | 4,830 |
Other Noncurrent Assets [Member] | Derivative Financial Instruments, Assets [Member] | Level 1 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 0 | 0 | 0 |
Other Noncurrent Assets [Member] | Derivative Financial Instruments, Assets [Member] | Level 2 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | 3,454 | 4,159 | 4,830 |
Other Noncurrent Assets [Member] | Derivative Financial Instruments, Assets [Member] | Level 3 [Member] | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | |
Total assets measured at fair value | $ 0 | $ 0 | $ 0 |