Number of stock option plans which are frozen to future issuance.

No definition available.

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, 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 (a)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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- Definition

Period from grant date that an equity-based award expires, 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 (a)(2)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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- 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=6415400&loc=d3e5070-113901

+ Details

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Balance Type:	na
Period Type:	instant

- Details

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Period Type:	duration

- Definition

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=6415400&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=6415400&loc=d3e5070-113901

+ Details

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Balance Type:	na
Period Type:	instant

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=gnbc_OptionPlan2006Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=gnbc_OptionPlan2010Member
Namespace Prefix:
Data Type:	na
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- Details

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Employee Benefits (Details)	0 Months Ended
Employee Benefits (Details)	Jun. 30, 2010	Jun. 21, 2006	Mar. 31, 2015 item	Jul. 14, 2014	Dec. 31, 2014
Stock Options
Number of stock option plans frozen			3
2014 Plan
Employee Benefits
Number of shares or units authorized for grants				1,273,838
2014 Plan \| Employee And Directors Time Based Options
Stock Options
Options outstanding			31,000		11,000
2010 Option Plan \| Employee And Directors Stock Options
Employee Benefits
Number of shares or units authorized for grants	2,239,906
Stock Options
Vesting period	4 years
2010 Option Plan \| Employee And Directors Time Based Options
Stock Options
Options outstanding			422,447		425,996
2010 Option Plan \| Employee And Directors Performance Options
Stock Options
Options outstanding			1,652,588		1,674,511
2006 Option Plan
Stock Options
Term of awards		10 years
2006 Option Plan \| Employee And Directors Stock Options
Employee Benefits
Number of shares or units authorized for grants		450,000
Stock Options
Options outstanding			362,500
Vesting period		4 years
Redstone Option Plan \| Employee And Directors Stock Options
Stock Options
Options outstanding			297,278		297,278