Equity Compensation Plans - Stock Option Activity (Details) - Stock Option Plan 2014 And 2003 - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of Shares
Beginning balance, outstanding (in shares)	3,418	4,053	4,766
Granted (in shares)	3,237	0	66
Exercised (in shares)	0	(22)	(623)
Forfeited or expired (in shares)	(1,451)	(613)	(156)
Ending balance, outstanding (in shares)	5,204	3,418	4,053
Number of Shares, Exercisable (in shares)	1,808
Weighted Average Exercise Price
Beginning balance, outstanding (in dollars per share)	$ 28.55	$ 28.95	$ 27.27
Granted (in dollars per share)	4.24	0	21.28
Exercised (in dollars per share)	0	24.99	15.53
Forfeited or expired (in dollars per share)	25.31	31.28	28.2
Ending balance, outstanding (in dollars per share)	14.33	$ 28.55	$ 28.95
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 30.20
Weighted Average Remaining Contractual Term (Years)	6 years 9 months 18 days
Weighted Average Remaining Contractual Term, Exercisable (Years)	3 years
Aggregate Intrinsic Value	$ 0
Aggregate Intrinsic Value, Exercisable	$ 0

For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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- Definition

Weighted average price of options that were either forfeited or expired.