Summary of Significant Accounting Policies - Earnings Per Share (Detail)	12 Months Ended
Dec. 31, 2017 shares
Accounting Policies [Abstract]
Number of shares of Common stock received for each exchangeable share (in shares)	1

Number of shares of common stock received for each exchangeable share.

No definition available.

Name:	pwr_NumberOfSharesOfCommonStockReceivedForEachExchangeableShare
Namespace Prefix:	pwr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration