Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Jul. 31, 2014	Jul. 31, 2013
Income Statement [Abstract]
Revenues	$ 141,387	$ 128,558
Operating expenses:
Cost of operations	98,766	88,419
General and administration	16,840	15,078
Depreciation and amortization	16,368	15,197
Environmental remediation charge	75
Severance and reorganization costs		107
Expense from divestiture, acquisition and financing costs		20
Total operating expenses	132,049	118,821
Operating income	9,338	9,737
Other expense (income):
Interest income	(88)	(12)
Interest expense	9,551	9,359
Loss from equity method investments		977
Gain on derivative instruments	(69)	(654)
Other income	(192)	(138)
Other expense, net	9,202	9,532
Income from continuing operations before income taxes and discontinued operations	136	205
Provision for income taxes	290	319
Loss from continuing operations before discontinued operations	(154)	(114)
Discontinued operations:
Income from discontinued operations (net of income tax provision of $0 and $0)		329
Loss on disposal of discontinued operations (net of income tax provision of $0 and $0)		(378)
Net loss	(154)	(163)
Less: Net income attributable to noncontrolling interests	136	28
Net loss attributable to common stockholders	(290)	(191)
Amounts attributable to common stockholders:
Loss from continuing operations before discontinued operations	(290)	(142)
Income from discontinued operations, net of tax		329
Loss on disposal of discontinued operations, net of tax		(378)
Net loss attributable to common stockholders	$ (290)	$ (191)
Basic and diluted earnings per share:
Loss from continuing operations before discontinued operations	$ (0.01)	$ 0.00
Income from discontinued operations, net of tax		$ 0.01
Loss on disposal of discontinued operations, net of tax		$ (0.01)
Net loss per common share	$ (0.01)	$ 0.00
Basic and diluted weighted average common shares outstanding	40,123	39,662