Quarterly report pursuant to Section 13 or 15(d)

Marketable Securities - Continuous Unrealized Loss Position (Details)

v3.8.0.1
Marketable Securities - Continuous Unrealized Loss Position (Details)
$ in Thousands
Sep. 30, 2017
USD ($)
Investments in an Unrealized Loss Position  
Fair Value $ 1,297,066
Gross Unrealized Losses, less than 12 months (4,628) [1]
Gross Unrealized Losses, 12 months or more 1,500
Corporate debt securities  
Investments in an Unrealized Loss Position  
Fair Value 581,581
Gross Unrealized Losses, less than 12 months (1,530) [1]
U.S. Government agency securities  
Investments in an Unrealized Loss Position  
Fair Value 341,545
Gross Unrealized Losses, less than 12 months (1,586) [1]
U.S. Treasury securities  
Investments in an Unrealized Loss Position  
Fair Value 361,406
Gross Unrealized Losses, less than 12 months (1,484) [1]
Sovereign securities  
Investments in an Unrealized Loss Position  
Fair Value 12,534
Gross Unrealized Losses, less than 12 months $ (28) [1]
[1] As of September 30, 2017, the amount of total gross unrealized losses related to investments that had been in a continuous loss position for 12 months or more was $1.5 million.