Equity Award Plans - Summary of Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Number of Shares
Options granted	0	0
2006 and 2013 Plan [Member] | Stock Options [Member]
Number of Shares
Balance at beginning of period	389,000	500,000
Options forfeited and cancelled	(6,000)	(111,000)
Balance at end of period	383,000	389,000	500,000
Options exercisable as of December 31, 2021	353,000
Options vested as of December 31, 2021	353,000
Options vested and expected to vest as of December 31, 2021	380,000
Weighted Average Exercise Price Per Share
Balance at beginning of period	$ 23.57	$ 23.38
Options forfeited and cancelled	43.45	22.74
Balance at end of period	23.23	$ 23.57	$ 23.38
Options exercisable as of December 31, 2021	24.86
Options vested as of December 31, 2021	24.86
Options vested and expected to vest as of December 31, 2021	$ 23.36
Weighted Average Remaining Contractual Term (in Years)
Options outstanding	4 years 10 months 6 days	5 years 9 months 7 days	5 years 9 months 7 days
Options exercisable	4 years 7 months 17 days
Options vested	4 years 7 months 17 days
Options vested and expected to vest	4 years 9 months 29 days