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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Stock-Based Compensation - Narrative (Details) - USD ($) $ in Millions			12 Months Ended
	May 25, 2016	Apr. 12, 2010	Dec. 31, 2019	Dec. 31, 2018	May 21, 2018	Dec. 31, 2017	May 29, 2010
Stock Based Compensation Details [Line Items]
Number of options outstanding (in shares)			2,334,731
Shares of common stock outstanding			53,850,427	53,774,221
Intrinsic value of options outstanding			$ 0.0	$ 0.5
Intrinsic value of options exercisable			0.0	0.5
Intrinsic value of options exercised			0.0	0.1
Unrecognized compensation costs			1.0
General and Administrative Expense
Stock Based Compensation Details [Line Items]
Stock option based expenses			$ 0.9	$ 1.5
Director Stock Option Plan - 1999
Stock Based Compensation Details [Line Items]
Number of options outstanding (in shares)			485,000	500,000
Plan 2009
Stock Based Compensation Details [Line Items]
Number of options outstanding (in shares)			1,847,608	2,458,106
Shares approved and authorized (in shares)	2,500,000						5,000,000
Additional shares authorized (in shares)		2,000,000
Maximum number of shares to any individual (in shares)			1,000,000
Shares of common stock outstanding			1,868,302	1,853,925
Options transferred (in shares)			1,369,038
Plan 2016
Stock Based Compensation Details [Line Items]
Shares approved and authorized (in shares)	2,000,000				4,000,000
Maximum number of shares to any individual (in shares)	1,000,000
Shares of common stock outstanding			136,496	74,667
Plan 2016, Plan 2009 And Director Plan
Stock Based Compensation Details [Line Items]
Number of options outstanding (in shares)			5,167,739	4,352,391
Restricted Stock Units (RSUs)
Stock Based Compensation Details [Line Items]
RSUs outstanding (in shares)			62,680	175,591		188,629
Restricted Stock Units (RSUs) \| Plan 2009
Stock Based Compensation Details [Line Items]
RSUs outstanding (in shares)				14,377
Restricted Stock Units (RSUs) \| Plan 2016
Stock Based Compensation Details [Line Items]
RSUs outstanding (in shares)			62,680	161,214
Restricted Stock
Stock Based Compensation Details [Line Items]
Stock option based expenses			$ 0.2	$ 0.5
Unrecognized compensation costs			$ 0.1
Common Stock \| Plan 2016
Stock Based Compensation Details [Line Items]
Number of options outstanding (in shares)			2,835,131	1,394,285
Minimum \| Restricted Stock
Stock Based Compensation Details [Line Items]
Vesting period			1 year
Maximum \| Restricted Stock
Stock Based Compensation Details [Line Items]
Vesting period			3 years