Fair Value Measurement Fair Value Measurements, Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investment securities	$ 14,687	$ 23,967
LONG-TERM INVESTMENT SECURITIES	12,974	0
Assets, Fair Value Disclosure	31,216	26,333
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investment securities	0	0
LONG-TERM INVESTMENT SECURITIES	0
Assets, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investment securities	14,687	23,967
LONG-TERM INVESTMENT SECURITIES	12,974
Assets, Fair Value Disclosure	31,216	26,333
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investment securities	0	0
LONG-TERM INVESTMENT SECURITIES	0
Assets, Fair Value Disclosure	0	0
Prepaid Expenses and Other Current Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	3,555	2,366
Prepaid Expenses and Other Current Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	0	0
Prepaid Expenses and Other Current Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	3,555	2,366
Prepaid Expenses and Other Current Assets [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	0	0
Earn-out liability [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonfinancial Liabilities Fair Value Disclosure	26,300	17,300
Earn-out liability [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonfinancial Liabilities Fair Value Disclosure	0	0
Earn-out liability [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonfinancial Liabilities Fair Value Disclosure	0	0
Earn-out liability [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonfinancial Liabilities Fair Value Disclosure	26,300	17,300
Liabilities, Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonfinancial Liabilities Fair Value Disclosure	26,300	17,300
Liabilities, Total [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonfinancial Liabilities Fair Value Disclosure	0	0
Liabilities, Total [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonfinancial Liabilities Fair Value Disclosure	0	0
Liabilities, Total [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonfinancial Liabilities Fair Value Disclosure	$ 26,300	$ 17,300