XML 52 R39.htm IDEA: XBRL DOCUMENT v3.10.0.1
Marketable Securities - Maturities (Details)
$ in Thousands
Dec. 31, 2018
USD ($)
Amortized Cost  
Maturing in one year or less $ 269,092
Maturing after one year 236,092
Total amortized cost 505,184
Estimate Fair Value  
Maturing in one year or less 268,115
Maturing after one year 236,108
Total estimated fair value $ 504,223