Pro Forma Results Under Acquisition (Detail) - Mobile Industrial Robots (MiR) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Revenue	$ 2,303,737	$ 2,111,373
Net income	$ 464,602	$ 442,082
Net income per common share, basic	$ 2.73	$ 2.36
Net income per common share, diluted	$ 2.59	$ 2.30