The number of shares that can be issued under the plan as a result of the grant of non-statutory options.

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Amount of increase in additional paid in capital (APIC) resulting from a tax benefit associated with share-based compensation plan other than an employee stock ownership plan (ESOP). Includes, but is not limited to, excess tax benefit.

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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Disclosure of the aggregate tax benefit realized from the exercise of stock options and the conversion of similar instruments during the annual period.

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Amount of gain (loss) on sale or disposal of property, plant and equipment assets, excluding oil and gas property and timber property.

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Amount of gain (loss) on sale or disposal of assets, including but not limited to property plant and equipment, intangible assets and equity in securities of subsidiaries or equity method investee.

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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

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The cash inflow associated with the deconsolidation of a previously consolidated subsidiary or the sale of investment in consolidated subsidiaries (generally greater than 50 percent).

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The cash inflow from the issuance of common stock, preferred stock, treasury stock, stock options, and other types of equity.

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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.

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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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.

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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.

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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).

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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.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Price of a single share of a number of saleable stocks of a company.

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Number of new stock issued during the period.

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Stockholders' (Deficit) Equity - Additional Information (Detail) (USD $)	8 Months Ended	12 Months Ended			0 Months Ended
	Dec. 31, 2014	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2012	Feb. 09, 2014	Apr. 30, 2007
Limited Partners' Capital Account [Line Items]
Shares issued	0us-gaap_PreferredStockSharesIssued	0us-gaap_PreferredStockSharesIssued	0us-gaap_PreferredStockSharesIssued
Weighted average fair value stock options granted	$ 4.86	$ 4.22	$ 3.03	$ 4.14
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Total fair value of other stock awards vested	$ 1,866,000	$ 1,458,000	$ 2,475,000	$ 2,056,000
Tax benefits from additional paid-in-capital adjustments	84,000	0	96,000	254,000
Stock Options [Member]
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense	386,000	464,000	528,000	258,000
Aggregate intrinsic value of stock options exercised	31,000	23,000	0	0
Unrecognized stock-based compensation expense	1,093,000
Unrecognized stock-based compensation expense, weighted average period	1 year 7 months 6 days
Restricted Stock, Restricted Stock Units and Performance Stock Units [Member]
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense	1,202,000	1,861,000	1,609,000	1,485,000
Income taxes associated with stock-based compensation expense	0	0	0	0
Restricted Stock and Restricted Stock Unit [Member]
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense	2,438,000
Unrecognized stock-based compensation expense, weighted average period	1 year 8 months 12 days
Performance Stock Units [Member]
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense	2,505,000
Unrecognized stock-based compensation expense, weighted average period	3 months 18 days
Amended and Restated 1997 Employee Stock Purchase Plan [Member]
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense	52,000	79,000	99,000	113,000
Non-Employee Director [Member] \| Restricted Stock Awards [Member]
Limited Partners' Capital Account [Line Items]
Options vesting period	3 years
Casella-Altela Regional Environmental Services, LLC [Member]
Limited Partners' Capital Account [Line Items]
Membership interest	51.00%
Casella-Altela Regional Environmental Services, LLC [Member] \| Subsequent Event [Member]
Limited Partners' Capital Account [Line Items]
Undiscounted purchase consideration					3,500,000
Gain on divestiture					2,850,000
Casella-Altela Regional Environmental Services, LLC [Member] \| Altela, Inc. [Member] \| Subsequent Event [Member]
Limited Partners' Capital Account [Line Items]
Membership interest					49.00%
Maximum [Member]
Limited Partners' Capital Account [Line Items]
Preferred stock authorized to issue	944,000
Maximum [Member] \| 2006 Stock Incentive Plan [Member]
Limited Partners' Capital Account [Line Items]
Options vesting period	4 years
Options granted period	10 years
Maximum [Member] \| Casella-Altela Regional Environmental Services, LLC [Member] \| Subsequent Event [Member]
Limited Partners' Capital Account [Line Items]
Gain on sale of assets					1,050,000
Minimum [Member] \| 2006 Stock Incentive Plan [Member]
Limited Partners' Capital Account [Line Items]
Options vesting period	1 year
Class A Common Stock [Member]
Limited Partners' Capital Account [Line Items]
Issuances of Class A common stock			11,500,000
Share price			$ 4.00
Net proceeds from the registered public offering			$ 42,184,000
Common stock, issued shares	1,200,000
Number of shares available for future grant	376,000
Class A Common Stock [Member] \| 1997 Non-Employee Director Stock Option Plan [Member]
Limited Partners' Capital Account [Line Items]
Common stock, issued shares	200,000
Class A Common Stock [Member] \| 2006 Stock Incentive Plan [Member]
Limited Partners' Capital Account [Line Items]
Common stock, issued shares						2,475,000
Number of shares available for future grant	1,010,000