Cash Equivalents and Investments - Unrealized Loss Position (Details) $ in Millions	Jun. 30, 2020 USD ($) security	Dec. 31, 2019 USD ($) security
Unrealized loss position, number of positions
Number of held securities in an unrealized loss position | security	6	11
Unrealized loss position, aggregate fair value
Unrealized loss position | $	$ 32.0	$ 82.1