Employee stock purchase plan share purchase offering period.

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Represents the remaining vesting term for the repriced awards.

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Minimum period for vesting.

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Number of monthly installments.

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Number of shares of common stock outstanding increase percentage.

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Share based compensation arrangement by share based payment award options closing stock price.

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The period prior to the expiration date of the stock appreciation rights after which the repriced awards are vested and exercisable.

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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Amount of cash outflow to satisfy an employee's income tax withholding obligation as part of a net-share settlement of a share-based award.

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The number of restricted shares issued as compensation, net of shares for the payment of withholding taxes. This element is to be used only if shares are used in lieu of cash to satisfy all or a portion of withholding taxes.

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No definition available.

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Amounts payable for money transfers, money orders, and consumer payment service arrangements. Settlement liabilities include amounts payable to intermediaries for global payment transfers.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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Per share weighted average intrinsic value of equity-based compensation awards granted. Excludes stock and unit options.

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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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Weighted average remaining contractual term for equity-based awards excluding options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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Number of additional shares authorized for issuance under an established share-based compensation plan.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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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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An excess of the fair value of the modified award over the fair value of the award immediately before the modification.

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Number of share instruments newly issued under a share-based compensation plan.

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Percentage of vesting of share-based compensation awards.

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Intrinsic value of equity-based compensation awards vested. Excludes stock and unit options.

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No definition available.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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Purchase price of common stock expressed as a percentage of its fair value.

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Stock-based compensation - Narrative (Details) $ / shares in Units, $ in Thousands		1 Months Ended		12 Months Ended
	Dec. 18, 2014 USD ($) installment $ / shares shares	Feb. 28, 2011 shares	Apr. 30, 2010 shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 $ / shares shares	Dec. 31, 2014 $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remitted cash to appropriate tax authorities \| $				$ 954	$ 998	$ 615
Stock Appreciation Units (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options to purchase shares, outstanding (in shares)				192,872	239,824
Intrinsic value of options exercised \| $				$ 100	$ 200	500
Number of days for stock price to be traded above mentioned price				20 days
Minimum closing stock price (USD per share) \| $ / shares				$ 15.00
Share-based compensation expense (gain) \| $				$ (100)	(300)
Stock grants vested value \| $				$ 0	$ 0	3,700
Employee stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options to purchase shares, outstanding (in shares)				3,202,745	3,933,529
Shares available for future grant (in shares)				1,102,323	959,136
Authorized for issuance (in shares)				1,947,667
Unrecognized stock-based compensation expense \| $				$ 1,800
Fair value of options vested \| $				2,300	$ 1,500	3,900
Intrinsic value of options exercised \| $				$ 2,400	$ 3,000	$ 9,700
Weighted-average fair value of options granted (USD per share) \| $ / shares				$ 4.03	$ 4.43	$ 7.05
Remaining weighted-average period				1 year 9 months 12 days
Stock Option and Restricted Stock Unit Activity
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Market-based restricted stock units (in shares)				800,000
Weighted-average fair value granted (USD per share) \| $ / shares							$ 4.72
Number of days for stock price to be traded above mentioned price				20 days
Minimum closing stock price (USD per share) \| $ / shares				$ 15.00
Share-based compensation expense (gain) \| $						$ 4,800
Stock Option and Restricted Stock Unit Activity \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value granted (USD per share) \| $ / shares								$ 1.65
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding (in shares)				2,486,028	2,404,637
Unrecognized stock-based compensation expense \| $				$ 13,200
Remaining weighted-average period				2 years 1 month 6 days
Market-based restricted stock units (in shares)				1,446,940
Weighted-average fair value granted (USD per share) \| $ / shares				$ 6.83	$ 7.86	$ 12.33
Stock grants vested value \| $				$ 9,800	$ 7,600	$ 1,600
Aggregate intrinsic value, vested \| $				$ 7,400	$ 6,400	$ 2,800
Common stock withheld shares (in shares)				147,572	126,999	49,838
Remitted cash to appropriate tax authorities \| $				$ 1,000	$ 1,000	$ 600
Vested (in shares)				1,123,893
Market-based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards expiration period from date of grant				7 years
Remaining weighted-average period				3 years 6 months
Market-based restricted stock units (in shares)				695,000
Weighted-average fair value granted (USD per share) \| $ / shares				$ 5.82
Vested (in shares)				0
Employee service share-based compensation, nonvested awards, compensation not yet recognized, stock options \| $				$ 2,900
Remaining contractual term				6 years 6 months
Stock Appreciation Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options to purchase shares, outstanding (in shares)				200,000
Liability for settlement \| $				$ 600	$ 800
2004 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options to purchase shares, outstanding (in shares)				273,685
Shares available for future grant (in shares)				0
2007 Stock Appreciation Grants Plan \| Stock Appreciation Units (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding (in shares)				27,872
2010 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant (in shares)				835,575
Shares outstanding (in shares)				5,553,442
Awards expiration period from date of grant				10 years
Maximum aggregate number of shares of common stock that may be issued (in shares)			865,420	8,000,000
Number of shares of common stock outstanding increase percentage			3.50%
2010 Equity Incentive Plan \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price, percentage of fair value of common stock on grant date				100.00%
Options vesting period				3 years
2010 Equity Incentive Plan \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options vesting period				4 years
2010 Equity Incentive Plan \| Nonqualified Stock Options \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price, percentage of fair value of common stock on grant date				85.00%
2010 ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant (in shares)				474,462
Maximum aggregate number of shares of common stock that may be issued (in shares)		342,568		600,000
Number of shares of common stock outstanding increase percentage		3.50%
Offering period				12 months
2011 Inducement Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant (in shares)				266,748
Shares outstanding (in shares)				556,646
Exercise price, percentage of fair value of common stock on grant date		100.00%
Awards expiration period from date of grant		10 years
Maximum aggregate number of shares of common stock that may be issued (in shares)		750,000
Authorized for issuance (in shares)							100,000
2014 Repricing Offer \| Stock Appreciation Units (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued under repricing offer (in shares)	87,354
2014 Repricing Offer \| Stock Options and Stock Appreciation Rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued under repricing offer (in shares)	2,373,692
Incremental compensation cost \| $	$ 900
Unrecognized stock-based compensation expense \| $	$ 2,600
Exercise price per share (USD per share) \| $ / shares	$ 3.50
Percentage of shares subject to repriced eligible stock	50.00%
Number of monthly installments \| installment	12
Remaining vesting term	60 days
Period prior to expiration date when repriced awards vested and become exercisable	60 days
2014 Repricing Offer \| Stock Options and Stock Appreciation Rights \| Vesting In 12 Equal Monthly Installments
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares subject to repriced eligible stock	50.00%
2014 Repricing Offer \| Stock Options and Stock Appreciation Rights \| 60th Day Prior to Expiration Date
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares subject to repriced eligible stock	100.00%
2014 Repricing Offer \| Employee stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued under repricing offer (in shares)	1,948,631