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Share-Based Compensation - Performance Restricted Stock Units - Activity (Details) - PRSUs - $ / shares shares in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Performance Restricted Stock (Units)
Outstanding at beginning of period (in shares)	333	260
Granted (in shares)	189	292
Performance condition adjustments (in shares)	(195)	(145)
Released (in shares)	(22)	(78)
Forfeited (in shares)	0	0
Outstanding at end of period (in shares)	305	329
Weighted Average Grant-Date Fair Value (in dollars per share)
Outstanding at the beginning of period (in dollars per share)	$ 8.84	$ 16.77
Granted (in dollars per share)	12.59	3.68
Performance condition adjustments (in dollars per share)	7.83	3.54
Released (in dollars per share)	13.63	15.43
Forfeited (in dollars per share)	0	0
Outstanding at end of period (in dollars per share)	$ 12.56	$ 11.09

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Share-based Compensation Arrangement By Share-based Payment Award, Equity Instruments Other Than Options, Adjustments In Period, Weighted Average Grant Date Fair Value

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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