Equity Awards - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net cash proceeds related to stock options exercised	$ 100	$ 1,200	$ (1,800)
Aggregate intrinsic value of stock options exercised	24	2,000	17,400
Stock-based compensation cost which has not yet been recognized	$ 37,600
Stock-based compensation cost recognized period, in months	2 years
Restricted stock awarded subject to performance condition (in shares)	443,000
Tax windfall related to share-based payment arrangements	$ 18	$ 2,800	$ 4,000
2018 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term of the awards granted under the plan	10 years
Additional shares authorized for grants (in shares)	700,000
Shares available for issuance (in shares)	404,787
2014 Capella Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance (in shares)	1,020,818