Stockholders' Equity - Employee Stock Purchase Plan (Details) - Employee Stock Purchase Plan - USD ($)	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee purchase price as a percentage of stock price	85.00%
Maximum annual contribution per employee	$ 25,000
Risk-free interest rate, minimum	0.10%	0.10%	0.10%
Risk-free interest rate, maximum	0.50%	0.50%	0.50%
Minimum expected volatility rate inputs for fair value measurement (in percent)	30.00%	30.00%	30.00%
Maximum expected volatility rate inputs for fair value measurement (in percent)	40.00%	40.00%	40.00%
Dividend yield (in percent)	0.00%	0.00%	0.00%
Weighted-average expected life	6 months 4 days	6 months 4 days	6 months 4 days
Common stock issued during period (in shares)	410,000	302,000	327,000
Number of shares authorized (in shares)	3,000,000

Fair market value of common stock, Percentage.

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- Definition

Share based compensation arrangement by share based payment award maximum amount per employee.

+ References

No definition available.

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- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

+ References

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- Definition

The estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

No definition available.

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- Definition

The estimated measure of the minimum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

No definition available.

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- Definition

The maximum risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

No definition available.

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- Definition

The minimum risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

No definition available.

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- Definition

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.

+ References

No definition available.

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- Definition

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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- Definition

Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

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- Definition

Number of shares issued during the period as a result of an employee stock purchase plan.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-Name Accounting Standards Codification
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-SubTopic 10
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