Net Income Per Share Information (Basic and Diluted Net Income Per Common Share) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Numerator:
Net income attributable to Waste Connections for basic and diluted earnings per share	$ 138,682	$ 123,656	$ 263,551	$ 138,530
Denominator:
Basic shares outstanding	263,691,172	263,387,338	263,757,179	263,225,541
Dilutive effect of equity-based awards	640,857	722,256	695,606	781,766
Diluted shares outstanding	264,332,029	264,109,594	264,452,785	264,007,307