Acquisitions - Business Acquisition Purchase Price Allocation Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Business Combinations [Abstract]
Value of Quanta common stock and exchangeable shares issued		$ 10,127
Cash paid or payable	$ 42,211	110,428
Contingent consideration	15,400	1,001
Fair value of total consideration transferred or estimated to be transferred	57,611	121,556
Current assets	16,489	35,188
Property and equipment	30,649	44,140
Other assets	1,972	4
Identifiable intangible assets	8,327	24,987
Current liabilities	(7,349)	(24,633)
Deferred tax liabilities, net	(13,267)	(4,912)
Other long-term liabilities	(5,326)	(5,606)
Non-controlling interests		747
Total identifiable net assets	31,495	69,915
Goodwill	26,116	51,641
Fair value of total consideration transferred	$ 57,611	$ 121,556