Subsidiary Guarantors - Schedule of Condensed Consolidating Balance Sheet (Detail) (USD $) In Thousands, unless otherwise specified	Jul. 31, 2014	Apr. 30, 2014	Jul. 31, 2013	Apr. 30, 2013
CURRENT ASSETS:
Cash and cash equivalents	$ 2,595	$ 2,464	$ 2,919	$ 1,755
Restricted cash	76	76
Accounts receivable - trade, net	59,212	52,603
Refundable income taxes	462	465
Prepaid expenses	8,359	7,176
Inventory	4,191	3,905
Deferred income taxes	2,331	2,502
Other current assets	1,314	1,255
Current assets of discontinued operations	365	359
Total current assets	78,905	70,805
Property, plant and equipment, net	403,306	403,424
Goodwill	119,139	119,139
Intangible assets, net	12,733	13,420
Restricted assets	703	681
Cost method investments	16,752	16,752
Investments in subsidiaries
Other non-current assets	23,687	24,205
Non-current assets of discontinued operations	1,377	1,471
Total non-current assets	577,697	579,092
Intercompany receivable
Total assets	656,602	649,897	674,744
CURRENT LIABILITIES:
Current maturities of long-term debt and capital leases	877	885
Accounts payable	47,372	51,788
Accrued payroll and related expenses	4,602	6,062
Accrued interest	12,955	6,087
Current accrued capping, closure and post-closure costs	4,669	7,312
Other accrued liabilities	20,000	17,612
Total current liabilities	90,475	89,746
Long-term debt and capital leases, less current maturities	511,192	507,134
Accrued capping, closure and post-closure costs, less current portion	38,846	37,342
Deferred income taxes	6,956	6,954
Other long-term liabilities	16,749	17,258
STOCKHOLDERS' (DEFICIT) EQUITY:
Casella Waste Systems, Inc. stockholders (deficit)' equity	(7,777)	(8,407)
Noncontrolling interests	161	(130)
Total stockholders' (deficit) equity	(7,616)	(8,537)
Total liabilities and stockholders' (deficit) equity	656,602	649,897
Parent [Member]
CURRENT ASSETS:
Cash and cash equivalents	1,992	2,151	2,320	1,260
Restricted cash
Accounts receivable - trade, net	431	534
Refundable income taxes	462	465
Prepaid expenses	3,640	2,617
Inventory
Deferred income taxes	2,331	2,502
Other current assets	296	312
Current assets of discontinued operations
Total current assets	9,152	8,581
Property, plant and equipment, net	4,160	4,104
Goodwill
Intangible assets, net	136	159
Restricted assets
Cost method investments	16,752	16,752
Investments in subsidiaries	(25,882)	(36,006)
Other non-current assets	13,316	13,874
Non-current assets of discontinued operations
Total non-current assets	8,482	(1,117)
Intercompany receivable	538,820	543,291
Total assets	556,454	550,755
CURRENT LIABILITIES:
Current maturities of long-term debt and capital leases	86	84
Accounts payable	17,345	22,678
Accrued payroll and related expenses	701	1,212
Accrued interest	12,950	6,084
Current accrued capping, closure and post-closure costs
Other accrued liabilities	7,674	7,289
Total current liabilities	38,756	37,347
Long-term debt and capital leases, less current maturities	509,018	504,836
Accrued capping, closure and post-closure costs, less current portion
Deferred income taxes	6,956	6,954
Other long-term liabilities	9,501	10,025
STOCKHOLDERS' (DEFICIT) EQUITY:
Casella Waste Systems, Inc. stockholders (deficit)' equity	(7,777)	(8,407)
Noncontrolling interests
Total stockholders' (deficit) equity	(7,777)	(8,407)
Total liabilities and stockholders' (deficit) equity	556,454	550,755
Guarantor [Member]
CURRENT ASSETS:
Cash and cash equivalents	261	271	299	253
Restricted cash	76	76
Accounts receivable - trade, net	58,769	51,983
Refundable income taxes
Prepaid expenses	4,710	4,557
Inventory	4,151	3,852
Deferred income taxes
Other current assets	1,011	936
Current assets of discontinued operations	365	359
Total current assets	69,343	62,034
Property, plant and equipment, net	398,497	398,670
Goodwill	119,139	119,139
Intangible assets, net	12,597	13,261
Restricted assets	703	681
Cost method investments	1,932	1,932
Investments in subsidiaries
Other non-current assets	10,371	10,331
Non-current assets of discontinued operations	1,377	1,471
Total non-current assets	544,616	545,485
Intercompany receivable	(501,875)	(506,348)
Total assets	112,084	101,171
CURRENT LIABILITIES:
Current maturities of long-term debt and capital leases	791	801
Accounts payable	29,562	28,286
Accrued payroll and related expenses	3,900	4,849
Accrued interest	5	3
Current accrued capping, closure and post-closure costs	4,666	7,309
Other accrued liabilities	12,098	10,081
Total current liabilities	51,022	51,329
Long-term debt and capital leases, less current maturities	2,174	2,298
Accrued capping, closure and post-closure costs, less current portion	38,809	37,306
Deferred income taxes
Other long-term liabilities	7,166	7,149
STOCKHOLDERS' (DEFICIT) EQUITY:
Casella Waste Systems, Inc. stockholders (deficit)' equity	12,913	3,089
Noncontrolling interests
Total stockholders' (deficit) equity	12,913	3,089
Total liabilities and stockholders' (deficit) equity	112,084	101,171
Non-Guarantor [Member]
CURRENT ASSETS:
Cash and cash equivalents	342	42	300	242
Restricted cash
Accounts receivable - trade, net	12	86
Refundable income taxes
Prepaid expenses	9	2
Inventory	40	53
Deferred income taxes
Other current assets	7	7
Current assets of discontinued operations
Total current assets	410	190
Property, plant and equipment, net	649	650
Goodwill
Intangible assets, net
Restricted assets
Cost method investments
Investments in subsidiaries
Other non-current assets
Non-current assets of discontinued operations
Total non-current assets	649	650
Intercompany receivable	(38,877)	(38,875)
Total assets	(37,818)	(38,035)
CURRENT LIABILITIES:
Current maturities of long-term debt and capital leases
Accounts payable	465	824
Accrued payroll and related expenses	1	1
Accrued interest
Current accrued capping, closure and post-closure costs	3	3
Other accrued liabilities	228	242
Total current liabilities	697	1,070
Long-term debt and capital leases, less current maturities
Accrued capping, closure and post-closure costs, less current portion	37	36
Deferred income taxes
Other long-term liabilities	82	84
STOCKHOLDERS' (DEFICIT) EQUITY:
Casella Waste Systems, Inc. stockholders (deficit)' equity	(38,795)	(39,095)
Noncontrolling interests	161	(130)
Total stockholders' (deficit) equity	(38,634)	(39,225)
Total liabilities and stockholders' (deficit) equity	(37,818)	(38,035)
Elimination [Member]
CURRENT ASSETS:
Cash and cash equivalents
Restricted cash
Accounts receivable - trade, net
Refundable income taxes
Prepaid expenses
Inventory
Deferred income taxes
Other current assets
Current assets of discontinued operations
Total current assets
Property, plant and equipment, net
Goodwill
Intangible assets, net
Restricted assets
Cost method investments	(1,932)	(1,932)
Investments in subsidiaries	25,882	36,006
Other non-current assets
Non-current assets of discontinued operations
Total non-current assets	23,950	34,074
Intercompany receivable	1,932	1,932
Total assets	25,882	36,006
CURRENT LIABILITIES:
Current maturities of long-term debt and capital leases
Accounts payable
Accrued payroll and related expenses
Accrued interest
Current accrued capping, closure and post-closure costs
Other accrued liabilities
Total current liabilities
Long-term debt and capital leases, less current maturities
Accrued capping, closure and post-closure costs, less current portion
Deferred income taxes
Other long-term liabilities
STOCKHOLDERS' (DEFICIT) EQUITY:
Casella Waste Systems, Inc. stockholders (deficit)' equity	25,882	36,006
Noncontrolling interests
Total stockholders' (deficit) equity	25,882	36,006
Total liabilities and stockholders' (deficit) equity	$ 25,882	$ 36,006