Stock-Based Compensation - Stock Option Activity (Details) - $ / shares	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of Options
Outstanding at beginning of year (in shares)	1,116,750	1,039,750	1,191,125
Granted (in shares)	0	176,000	81,000
Expired or forfeited (in shares)	(184,250)	(99,000)	(232,375)
Outstanding at end of year (in shares)	932,500	1,116,750	1,039,750
Exercisable at end of year (in shares)	932,500	1,116,750	1,039,750
Weighted- Average Exercise Price
Outstanding at beginning of year (in dollars per share)	$ 6.34	$ 8.39	$ 10.48
Granted (in dollars per share)	0.00	0.96	1.58
Expired or forfeited (in dollars per share)	14.72	18.32	16.72
Outstanding at end of year (in dollars per share)	4.68	6.34	8.39
Exercisable at end of year (in dollars per share)	4.68	6.34	8.39
Weighted-average fair value of options granted during the year (in dollars per share)	$ 0.00	$ 0.68	$ 1.11

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iii)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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- Definition

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

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

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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

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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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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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