Stock-Based Compensation and Compensation Plans - Summary of Stock Option Activity (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Common Stock Options
Outstanding at beginning of year (in shares)	6,780	5,903	5,284
Granted (in shares)	2,630	1,610	1,293
Exercised (in shares)	(109)	(80)	0
Expired or forfeited (in shares)	(373)	(653)	(674)
Outstanding at end of year (in shares)	8,928	6,780	5,903
Weighted Average Exercise Price
Outstanding at beginning of year (in dollars per share)	$ 10.89	$ 13.72	$ 19.58
Granted (in dollars per share)	6.10	4.26	1.67
Exercised (in dollars per share)	2.89	2.66	0
Expired or forfeited (in dollars per share)	19.49	21.16	36.54
Outstanding at end of year (in dollars per share)	$ 9.22	$ 10.89	$ 13.72
Options exercisable at end of year (in shares)	4,462	3,317	2,709
Weighted average grant date fair value (per share) of options granted during the period (in dollars per share)	$ 13.51	$ 3.37	$ 1.20