Stock-based Compensation - Award Activity (Details) - shares shares in Thousands	3 Months Ended
Mar. 31, 2020	Dec. 31, 2019
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Equity awards outstanding, beginning of year (in shares)	5,901
Granted (in shares)	1,429
Exercised (in shares)	(7)
Expired or forfeited (in shares)	(281)
Equity awards outstanding, end of period (in shares)	7,042
RSUs
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Equity awards outstanding, beginning of year (in shares)	158	58
Granted (in shares)	100
Exercised (in shares)	0
Expired or forfeited (in shares)	0
Equity awards outstanding, end of period (in shares)	158
PSOs
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Equity awards outstanding, beginning of year (in shares)	684	837
Granted (in shares)	0
Exercised (in shares)	0
Expired or forfeited (in shares)	(153)
Equity awards outstanding, end of period (in shares)	684

Number of non-option equity instruments exercised by participants.

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Number of shares under non-option equity instrument agreements that were either cancelled or expired.

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Net number of non-option equity instruments granted to participants.

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Number of equity instruments other than options outstanding, including both vested and non-vested instruments.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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Gross number of share options (or share units) granted during the period.

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Number of options outstanding, including both vested and non-vested options.

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Number of share options (or share units) exercised during the current period.

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