Equity Award Plans - Summary of Stock Options Activity (Details) - 2006 and 2013 Plan [Member] - Stock Options [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Number of Shares
Balance at beginning of period	435	500
Options forfeited and cancelled	(65)
Options exercisable	387
Options vested	387
Options vested and expected to vest	427
Weighted Average Exercise Price Per Share
Balance at beginning of period	$ 24.89	$ 23.38
Options forfeited and cancelled	13.29
Options exercisable	27.38
Options vested	27.38
Options vested and expected to vest	$ 25.28
Weighted Average Remaining Contractual Term (in Years)
Options outstanding	6 years 29 days	5 years 9 months 7 days
Options exercisable	5 years 9 months
Options vested	5 years 9 months
Options vested and expected to vest	6 years 10 days
Aggregate Intrinsic Value
Options outstanding	$ 0	$ 0