Stockholder's Equity and Stock-Based Compensation Expense - Activity Related to Stock Options, Restricted Stock Restricted Stock Unit Awards and Stock Appreciation Rights (Details) - shares	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2019
Stock Options and Stock Appreciation Rights
Ending balance (In shares)	815,791	766,659
Stock Options
Stock Options and Stock Appreciation Rights
Beginning balance (in shares)		785,890
Granted (in shares)		10,000
Exercised (in shares)		(24,500)
Cancelled/forfeited (in shares)		(4,731)
Ending balance (In shares)		766,659
Restricted Stock and Unit Awards
Restricted Stock and Unit Awards
Beginning balance (in shares)		1,044,125
Granted (in shares)		17,500
Vested (in shares)		(201,631)
Cancelled/forfeited (in shares)		(65,000)
Ending balance (in shares)	128,131	794,994
Stock Appreciation Rights
Stock Options and Stock Appreciation Rights
Beginning balance (in shares)		1,481,541
Granted (in shares)		0
Exercised (in shares)		(50,000)
Cancelled/forfeited (in shares)		(368,528)
Ending balance (In shares)	530,865	1,063,013

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

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

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- Definition

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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No definition available.

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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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No definition available.

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

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 718
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Number of share options (or share units) exercised during the current period.

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