Stock-Based Compensation, Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Stock Options Shares Outstanding, Beginning balance (in shares)	5,543
Granted (in shares)	1,697
Exercised (in shares)	(182)
Forfeited or expired (in shares)	(585)
Stock Options Shares Outstanding, Ending balance (in shares)	6,473	5,543
Options exercisable (in shares)	4,038
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Stock Options Outstanding, Weighted Average Exercise Price, Beginning balance (in usd per share)	$ 20.13
Granted, Weighted Average Exercise Price (in usd per share)	18.43
Exercised, Weighted Average Exercise Price (in usd per share)	13.77
Forfeited or expired, Weighted Average Exercise Price (in usd per share)	21.07
Stock Options Outstanding, Weighted Average Exercise Price, Ending balance (in usd per share)	19.77	$ 20.13
Options Exercisable, Weighted Average Exercise Price (in usd per share)	$ 19.25
Stock Options Outstanding, Weighted Average Remaining Contractual Term	6 years 2 months 23 days	6 years 3 months
Options exercisable, Weighted Average Remaining Contractual Term	4 years 10 months 20 days
Stock Options Outstanding, Aggregate Intrinsic Value	$ 2,005	$ 16,043
Options exercisable, Aggregate Intrinsic Value	$ 1,913