Stock Compensation Plans - Option Groups Outstanding (Parenthetical) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average exercise price for options outstanding (in dollars per share)	$ 15.97	$ 20.61
Weighted average exercise price for options exercisable (in dollars per share)	$ 20.98
Options outstanding, weighted average remaining contractual term	5 years 10 months 24 days
Options exercisable, weighted average remaining contractual term	2 years 10 months 24 days
All Other Grant Dates
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Other options exercise price range, lower range limit (in dollars per share)	$ 9.54
Other options exercise price range, upper range limit (in dollars per share)	32.72
Weighted average exercise price for options outstanding (in dollars per share)	21.45
Weighted average exercise price for options exercisable (in dollars per share)	$ 21.32
Options outstanding, weighted average remaining contractual term	3 years
Options exercisable, weighted average remaining contractual term	3 years