Stock-Based Compensation (Narrative) (Details) (USD $)	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic value of stock options outstanding	$ 81,400,000
Weighted-average remaining contractual term of stock options outstanding	7 years 7 months 6 days
Aggregate intrinsic value of stock options exercised	3,800,000	1,400,000
Unrecognized compensation expense	12,500,000
Unrecognized compensation expense, recognition period	1 year 6 months
Stock-based compensation expense	1,932,000	1,040,000
Aggregate intrinsic value of stock options exercisable	45,500,000
Weighted-average remaining contractual term of stock options exercisable	6 years 7 months 6 days
2005 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term of options	10 years
Minimum grant price, percent of common stock fair value	100.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	22,500
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	$ 6.7
1995 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	0
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	$ 0
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance	1,313,388
Stock-based compensation expense	$ 200,000	$ 100,000
Employee Stock Ownership Plan (ESOP), Plan Description	In 2013, the Company adopted an Employee Stock Purchase Plan (the ESPP), which authorized an aggregate of 2,000,000 shares of common stock to be purchased, which will increase 5% on each anniversary of its adoption up to a maximum of 3,000,000 shares. The ESPP allows employees to purchase shares of common stock of the Company at each purchase date through payroll deductions of up to a maximum of 15% of their compensation, at 85% of the lesser of the market price of the shares at the time of purchase or the market price on the beginning date of an option period (or, if later, the date during the option period when the employee was first eligible to participate).
2015 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance	25,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	6,974,441
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	$ 8.94
2015 Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Options Vesting Period	4 years
2015 Plan [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Options Vesting Period	6 months

The minimum grant-date exercise price of incentive stock options granted as a percent of the common stock share price.

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Maximum term of incentive stock options.

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It represents the stock options vesting period.

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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.

+ References

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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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Description of the plan, including the basis for determining contributions, the employee groups covered, and the nature and effect of significant matters affecting comparability of information for all periods presented. For leveraged ESOPs and pension reversion ESOPs, the description generally includes the basis for releasing shares and how dividends on allocated and unallocated shares are used.

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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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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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

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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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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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