Common stock Common Stock (ESPP B-S-M option pricing model assumptions) (Details) (USD $)	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012
ESPP plan details [Abstract]
Stock Shares Issued During Period, ESPP	215,039	0
Common stock (in shares) reserved for ESPP	373,010
Two Thousand Twelve Employee Stcok Purchase Plan [Member] \| Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%	0.00%
ESPP plan details [Abstract]
ESPP-Maximum Annual Purchase by Employee, Percent	15.00%
ESPP-Discount of market Price	85.00%
ESPP-Offering Period, Initial Offer	11 months
ESPP-Offering Period, Subsequent Offers	6 months
Share-based Comp, Per Share Wtd Avg Price of Shares Purchased	$ 13.92
Common stock (in shares) reserved for ESPP	193,920
Two Thousand Twelve Employee Stcok Purchase Plan [Member] \| Employee Stock [Member] \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (years)	6 months
Expected Volatility Rate	43.20%
Risk-free interest rate	0.14%
Two Thousand Twelve Employee Stcok Purchase Plan [Member] \| Employee Stock [Member] \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (years)	11 months
Expected Volatility Rate	50.00%
Risk-free interest rate	0.18%

Aggregate number of common shares reserved for future issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

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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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-Publisher FASB

-Name Accounting Standards Codification

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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

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The estimated measure of the 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.

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- Definition

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

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- Definition

The weighted average of per share prices paid for shares purchased on the open market for issuance to employees under the plan.

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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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-Publisher SEC

-Name Regulation S-X (SX)

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Share-based Compensation Arrangements by Share-based Payment Award, Discount of the lower of the fair market value of the Company's common stock on the first trading day of the offering period or on the last day of the offering period.

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Share-based Compensation Arrangements by Share-based Payment Award, ESPP First Offering Period

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