Employee Stock Plans - Performance Share Units Award Activity (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2020 $ / shares shares
Performance Shares
Number of PSUs
Non-vested beginning balance (in shares)	200
Granted (in shares)	132
Forfeited (in shares)	(25)
Non-vested ending balance (in shares)	307
Grant Date Fair Value Per Unit
Outstanding beginning balance (in dollars per share) | $ / shares	$ 19.82
Granted (in dollars per share) | $ / shares	25.75
Expired or cancelled (in dollars per share) | $ / shares	22.14
Outstanding ending balance (in dollars per share) | $ / shares	$ 22.18
Restricted Stock Units and Awards
Number of PSUs
Non-vested beginning balance (in shares)	577
Granted (in shares)	178
Forfeited (in shares)	(18)
Non-vested ending balance (in shares)	461