The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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

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Number of options outstanding, including both vested and non-vested options.

+ 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

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

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

+ 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 (c)(1)(i)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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No definition available.

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Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding.

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The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices.

+ References

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

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Weighted average remaining contractual term of outstanding stock options, 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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-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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Employee Benefit Plans (Details 1) - Officer and Employee Plans [Member] - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 11.82	$ 10.57	$ 10.62
Number Outstanding (in shares)	316,574	717,524	817,414
Options Outstanding, Weighted Average Remaining Life	3 years 8 months 5 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 11.82
Options, Number Exercisable (in shares)	293,119
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 11.56
6.60 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 6.60
Number Outstanding (in shares)	37,500
Options Outstanding, Weighted Average Remaining Life	4 years 2 months 12 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 6.60
Options, Number Exercisable (in shares)	37,500
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 6.60
6.80 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 6.80
Number Outstanding (in shares)	16,875
Options Outstanding, Weighted Average Remaining Life	3 years 2 months 1 day
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 6.80
Options, Number Exercisable (in shares)	16,875
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 6.80
9.48 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 9.48
Number Outstanding (in shares)	26,875
Options Outstanding, Weighted Average Remaining Life	5 years 2 months 12 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 9.48
Options, Number Exercisable (in shares)	26,875
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 9.48
9.60 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 9.60
Number Outstanding (in shares)	35,625
Options Outstanding, Weighted Average Remaining Life	6 years 2 months 1 day
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 9.60
Options, Number Exercisable (in shares)	35,625
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 9.60
11.67 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 11.67
Number Outstanding (in shares)	2,000
Options Outstanding, Weighted Average Remaining Life	3 years 29 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 11.67
Options, Number Exercisable (in shares)	2,000
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 11.67
11.76 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 11.76
Number Outstanding (in shares)	130,469
Options Outstanding, Weighted Average Remaining Life	1 year 11 months 5 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 11.76
Options, Number Exercisable (in shares)	130,469
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 11.76
14.40 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 14.40
Number Outstanding (in shares)	12,805
Options Outstanding, Weighted Average Remaining Life	1 year 1 month 28 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 14.40
Options, Number Exercisable (in shares)	12,805
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 14.40
15.05 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 15.05
Number Outstanding (in shares)	41,259
Options Outstanding, Weighted Average Remaining Life	7 years 9 months
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 15.05
Options, Number Exercisable (in shares)	17,804
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 15.05
31.96 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 31.96
Number Outstanding (in shares)	13,166
Options Outstanding, Weighted Average Remaining Life	1 month 28 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 31.96
Options, Number Exercisable (in shares)	13,166
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 31.96