Acquisitions (Details) - USD ($) $ / shares in Units, $ in Thousands					3 Months Ended								12 Months Ended
	Nov. 30, 2015	Sep. 29, 2014	Jan. 02, 2014	Jul. 22, 2013	Jun. 30, 2016	Mar. 25, 2016	Dec. 25, 2015	Sep. 25, 2015	Jun. 30, 2015	Mar. 27, 2015	Dec. 26, 2014	Sep. 26, 2014	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2016
Business Acquisition [Line Items]
Gross revenue					$ 169,532	$ 158,130	$ 157,743	$ 135,459	$ 149,087	$ 130,777	$ 143,228	$ 123,025	$ 620,864	$ 546,117	$ 475,677
Net service revenue					132,331	121,253	111,382	100,163	114,567	100,994	99,838	92,619	465,129	408,018	354,956
Operating income (loss)					10,261	$ (23,302)	$ 6,698	$ 7,673	10,703	$ 7,149	6,866	$ 5,992	1,330	30,710	20,921
Business Acquisition, Purchase Price Allocation [Abstract]
Other Payments to Acquire Businesses													1,161	2,644	1,124
Goodwill					(75,337)				(37,024)				(75,337)	(37,024)	(31,679)
Acquisition and integration expense													6,571	0	$ 0
Pipeline Services
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Revenue													695,916	772,628
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents	$ (355)
Business Acquisition, Cost Of Acquired Entity, Cash Paid in Year Two, Due in Period Two	7,500
Business Combination, Net Working Capital Adjustment	2,957															$ 2,354
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	(44,500)
Business Acquisition, Purchase Price Allocation [Abstract]
Cash	119,955
Purchase price of business	124,498
Goodwill	(60,294)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	(28,263)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets	(7,228)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	(3,552)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets	(20,683)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable	(2,544)
Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Accrued Compensation And Benefits	(7,201)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other	(5,110)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Long-term Debt	(6,485)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	(18,547)
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value	(490)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	124,498
Business Acquisition, Pro Forma Sales Revenue, Net, Services													515,705	562,441
Business Acquisition, Pro Forma Net Income (Loss)													$ (2,378)	$ 12,890
Business Acquisition, Pro Forma Earnings Per Share, Basic													$ (0.08)	$ 0.43
Business Acquisition, Pro Forma Earnings Per Share, Diluted													$ (0.08)	$ 0.42
NOVA Safety & Environmental
Business Acquisition [Line Items]
Business Acquisition, Cost Of Acquired Entity, Cash Paid in Year Two, Due in Period One		$ 508
Business Acquisition, Cost Of Acquired Entity, Cash Paid in Year Two, Due in Period Two		2,092
Additions for 2013 acquisitions		1,500									287
Business Combination, Net Working Capital Adjustment		$ 560
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles											(3,622)
Shares exchanged in business acquisitions		50,000
Business Acquisition, Purchase Price Allocation [Abstract]
Cash		$ 7,198
Common stock		323
Second cash payment due one year after closing date		$ 2,600
Goodwill											$ (3,683)
EMCOR Energy Services, Inc.
Business Acquisition [Line Items]
Business Combination, Net Working Capital Adjustment			$ 244
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles			(861)
Business Acquisition, Purchase Price Allocation [Abstract]
Cash			1,400
Purchase price of business			1,644
Goodwill			$ (247)
Utility Support Systems Inc.
Business Acquisition [Line Items]
Additions for 2013 acquisitions				$ 504
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles				$ (2,056)
Shares exchanged in business acquisitions				34,066
Business Acquisition, Purchase Price Allocation [Abstract]
Cash				$ 2,500
Common stock				295
Second cash payment due one year after closing date				1,803
Purchase price of business				5,027
Goodwill				$ (2,180)
Adjustment | Pipeline Services
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	0
Business Acquisition, Purchase Price Allocation [Abstract]
Goodwill	(4,379)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	1,857
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets	(48)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable	(43)
Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Accrued Compensation And Benefits	2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other	(100)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Long-term Debt	38
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	0
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value	490
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	(2,957)
Scenario, Previously Reported | Pipeline Services
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents	(355)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	(44,500)
Business Acquisition, Purchase Price Allocation [Abstract]
Goodwill	(64,673)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	(26,406)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets	(7,276)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	(3,552)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets	(20,683)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable	(2,587)
Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Accrued Compensation And Benefits	(7,199)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other	(5,210)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Long-term Debt	(6,447)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	(18,547)
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	$ 127,455
Contract Backlog
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life													1 year
Contract Backlog | Pipeline Services
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	1 year
Software Development | Pipeline Services
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	5 years
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ (1,000)
Software Development | Adjustment | Pipeline Services
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	0
Software Development | Scenario, Previously Reported | Pipeline Services
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	(1,000)
Customer Relationships
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life													7 years
Customer Relationships And Backlog | Pipeline Services
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	(43,500)
Customer Relationships And Backlog | Adjustment | Pipeline Services
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	0
Customer Relationships And Backlog | Scenario, Previously Reported | Pipeline Services
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ (43,500)
Pipeline Services Operating Segment
Business Acquisition [Line Items]
Gross revenue													$ 60,712
Net service revenue													48,379
Operating income (loss)													(7,476)
Business Acquisition, Purchase Price Allocation [Abstract]
Goodwill					$ (38,313)				$ 0				(38,313)	$ 0
Acquisition and integration expense													3,444
Corporate Segment | Pipeline Services
Business Acquisition [Line Items]
Business Acquisition, Severance And Personnel Costs													1,508
Business Acquisition, Purchase Price Allocation [Abstract]
Business Acquisition, Professional Services And Other Expenses													2,824
Business Acquisition, Lease Abandonment Expenses													2,239
Acquisition and integration expense													$ 6,571
Minimum | Customer Relationships | Pipeline Services
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	12 years
Maximum | Customer Relationships | Pipeline Services
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	15 years
Weighted Average | Software Development | Pipeline Services
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	5 years
Weighted Average | Customer Relationships | Pipeline Services
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years