Required holding period for employee purchase of common stock as defined by the employee stock purchase plan.

No definition available.

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- Definition

Discount rate from fair value on purchase date that participants pay for shares.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

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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.

+ Details

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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).

+ 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 (a)(3)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

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Data Type:	xbrli:sharesItemType
Balance Type:	na
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- Definition

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.

+ References

+ Details

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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

+ Details

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Data Type:	xbrli:sharesItemType
Balance Type:	na
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- Details

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- Details

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Stock-Based Compensation - Employee Stock Purchase Plan (Details) - shares	1 Months Ended		3 Months Ended	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Dec. 31, 2016	Dec. 31, 2017
Employee Stock Purchase Plan
Stock-based compensation
Total shares authorized				600,000
Shares available for future purchases				571,698
Employee Stock Purchase Plan
Stock-based compensation
Discount from the closing price on the exercise date (as a percent)			5.00%
Holding period for common stock purchased by plan participants				2 years
Shares issued to employee participants	12,341	15,961