Current Vulnerability Due to Certain Concentrations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Concentration Risks [Abstract]
Duration of business operations in Israel (in years)	P47Y
Credit Concentration Risk [Member] | Cash and Cash Equivalents and Short-term Investments [Member] | Bank of China [Member]
Concentration Risks [Abstract]
Concentration risk percentage (in hundredths)	13.90%
Credit Concentration Risk [Member] | Cash and Cash Equivalents and Short-term Investments [Member] | Deutsche Bank [Member]
Concentration Risks [Abstract]
Concentration risk percentage (in hundredths)	13.10%
Geographic Concentration [Member] | Outside Of United States [Member]
Concentration Risks [Abstract]
Cash and cash equivalents and short-term investments	$ 1,282,120
Geographic Concentration [Member] | Cash and Cash Equivalents and Short-term Investments [Member] | United States [Member]
Concentration Risks [Abstract]
Concentration risk percentage (in hundredths)	8.10%
Geographic Concentration [Member] | Cash and Cash Equivalents and Short-term Investments [Member] | Germany [Member]
Concentration Risks [Abstract]
Concentration risk percentage (in hundredths)	43.60%
Geographic Concentration [Member] | Cash and Cash Equivalents and Short-term Investments [Member] | Other Europe [Member]
Concentration Risks [Abstract]
Concentration risk percentage (in hundredths)	1.60%
Geographic Concentration [Member] | Cash and Cash Equivalents and Short-term Investments [Member] | Israel [Member]
Concentration Risks [Abstract]
Concentration risk percentage (in hundredths)	21.60%
Geographic Concentration [Member] | Cash and Cash Equivalents and Short-term Investments [Member] | People's Republic Of China [Member]
Concentration Risks [Abstract]
Concentration risk percentage (in hundredths)	6.90%
Geographic Concentration [Member] | Cash and Cash Equivalents and Short-term Investments [Member] | Other Asia [Member]
Concentration Risks [Abstract]
Concentration risk percentage (in hundredths)	1.70%
Geographic Concentration [Member] | Cash and Cash Equivalents and Short-term Investments [Member] | Other [Member]
Concentration Risks [Abstract]
Concentration risk percentage (in hundredths)	0.80%
Geographic Concentration [Member] | Cash and Cash Equivalents and Short-term Investments [Member] | Singapore [Member]
Concentration Risks [Abstract]
Concentration risk percentage (in hundredths)	8.10%
Geographic Concentration [Member] | Cash and Cash Equivalents and Short-term Investments [Member] | The Republic of China (Taiwan) [Member]
Concentration Risks [Abstract]
Concentration risk percentage (in hundredths)	7.60%
Geographic Concentration [Member] | Revenue [Member] | Outside Of United States [Member]
Concentration Risks [Abstract]
Concentration risk percentage (in hundredths)	77.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentration Risks [Abstract]
Concentration risk percentage (in hundredths)	16.10%	15.40%