Supplementary Balance Sheet Information (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Total cash and cash equivalents	$ 458,220	$ 471,156
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	460,662	474,279	$ 461,040	$ 451,370
Domestic
Total cash and cash equivalents	405,000	405,535
Foreign
Total cash and cash equivalents	53,220	65,621
Other long-term assets
Restricted cash included in other long-term assets	$ 2,442	$ 3,123