Common Stock and Share-Based Compensation - Restricted Stock Unit Activity (Details) - Restricted Stock Units (RSUs)	12 Months Ended
Dec. 31, 2018 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period (shares)	631,234
Stock units issued (shares)	855,483
Shares issued upon vesting of stock units (shares)	(215,925)
Stock units canceled or forfeited (shares)	(289,822)
Outstanding at end of period (shares)	980,970
Weighted average grant date fair value (USD per share) \| $ / shares	$ 11.44
Employees
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period (shares)	545,405
Stock units issued (shares)	759,814
Shares issued upon vesting of stock units (shares)	(176,881)
Stock units canceled or forfeited (shares)	(287,907)
Outstanding at end of period (shares)	840,431
Weighted average grant date fair value (USD per share) \| $ / shares	$ 11.35
Director
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period (shares)	85,829
Stock units issued (shares)	95,669
Shares issued upon vesting of stock units (shares)	(39,044)
Stock units canceled or forfeited (shares)	(1,915)
Outstanding at end of period (shares)	140,539
Weighted average grant date fair value (USD per share) \| $ / shares	$ 11.95

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

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)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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- Definition

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).

+ References

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- Definition

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.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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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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No definition available.

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- Definition

The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

+ References

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-Publisher FASB
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Number of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of any shares forfeited. Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

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