Employee Stock Plans - Stock Award Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock Option Activity
Outstanding beginning balance (in shares)	1,820,000
Granted (in shares)	50,000	50,000	0
Exercised (in shares)	(647,000)
Outstanding ending balance (in shares)	1,223,000	1,820,000
Stock Option Weighted Average Exercise Price Per Share
Outstanding begging balance (in dollars per share)	$ 15.02
Granted (in dollars per share)	32.64
Exercised (in dollars per share)	11.30
Outstanding ending balance (in dollars per share)	$ 17.71	$ 15.02
Stock Option Activity, Additional Disclosures
Options outstanding, Weighted average remaining contractual term	1 year 11 months 23 days
Options outstanding, Aggregate intrinsic value (in dollars)	$ 26.2
Options vested and exercisable, Number of Options (in shares)	1,075,000
Options vested and exercisable, Weighted average exercise price per share (in dollars per share)	$ 17.47
Options vested and exercisable, Weighted average remaining contractual term	1 year 11 months 4 days
Options exercisable, Aggregate intrinsic value (in dollars)	$ 23.3