Represents the number of share-based compensation plans maintained by the entity.

No definition available.

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- Definition

The period of time in which the equity-based award expires.

+ References

No definition available.

+ Details

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- Definition

Number of additional shares authorized for issuance under an established share-based compensation plan.

+ References

No definition available.

+ Details

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Data Type:	xbrli:sharesItemType
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Period Type:	duration

- 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

- 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

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

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
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- Details

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

- Details

Name:	us-gaap_AwardTypeAxis=hdy_EmployeeAndDirectorsStockOptionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

SHARE-BASED COMPENSATION - General Information (Details)	Jan. 27, 2016 shares	Feb. 18, 2010 plan	Mar. 31, 2017 shares
SHARE-BASED COMPENSATION
Number of stock award plans prior to the adoption of 2010 plan \| plan		2
2010 Plan \| Stock options
SHARE-BASED COMPENSATION
Increase in the number of shares available for issuance	750,000
Period within which shares of common stock, options or restricted stock can be awarded under the 2010 plan		10 years
Number of shares issuable under the plan			2,000,000
Number of shares remaining available for issuance			783,460