Quarterly Results (Unaudited) (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2020		Sep. 30, 2020		Jun. 30, 2020		Mar. 31, 2020		Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Selected Quarterly Financial Information [Abstract]
Revenues	$ 3,169,188	[1]	$ 2,464,797	[1]	$ 2,580,632	[1]	$ 1,901,864	[1]	$ 2,044,941	[2]	$ 2,074,855	[2]	$ 2,035,579	[2]	$ 2,020,051	[2]	$ 10,116,481	[3]	$ 8,175,426	[3]	$ 8,138,365	[3]
Operating income	281,811	[1]	251,945	[1]	247,626	[1]	159,055	[1]	180,340	[2]	206,550	[2]	192,201	[2]	187,601	[2]	940,437		766,692		796,563
Net earnings	199,525		191,719		184,188		122,782		137,748		160,627		153,530		140,111		698,214		592,016		619,790
Net earnings attributable to shareholders	$ 198,620		$ 191,307		$ 183,869		$ 122,344		$ 137,326		$ 160,221		$ 153,149		$ 139,699		$ 696,140		$ 590,395		$ 618,199
Diluted earnings attributable to shareholders per share	$ 1.16		$ 1.12		$ 1.09		$ 0.71		$ 0.79		$ 0.92		$ 0.88		$ 0.80		$ 4.07		$ 3.39		$ 3.48
Basic earnings attributable to shareholders per share	$ 1.17		$ 1.14		$ 1.10		$ 0.73		$ 0.81		$ 0.94		$ 0.90		$ 0.81		$ 4.14		$ 3.45		$ 3.55

[1] During the fourth quarter of 2020, the Company’s services experienced record high airfreight tonnage and ocean volumes and high average sell rates and buy rates, when compared to the third quarter of 2020 and the prior year, as demand grew while capacity shortages persisted in particular on exports from North Asia. In the fourth quarter of 2020, the People's Republic of China, including Hong Kong, represented 34% of the Company’s total revenues and 27% of the Company’s total operating income. Airfreight services revenues accounted for the largest increase at 41% from the third quarter of 2020 to the fourth quarter of 2020 and represented 49% of the Company’s total revenues in the fourth quarter of 2020

[2] The fourth quarter of 2019 was significantly impacted by declines in results in our China operations due to the slowing of trade to and from China, which impacted overall freight movement around the globe. In the fourth quarter of 2019, the People's Republic of China, including Hong Kong, represented 25% of the Company’s total revenues and the Company’s total operating income

[3] In 2019, the Company revised its process to record the transfer, between its geographic operating segments, of revenues and the directly related cost of transportation and other expenses for freight service transactions between Company origin and destination locations. This change better aligns revenue reporting with the location where the services are performed, as well as the transactional reporting being developed as part of the Company’s new accounting systems and processes. The change in presentation had no impact on consolidated or segment operating income. The 2019 results also include the effect of changing the presentation of certain import services from a net to a gross basis, which increased segment revenues and directly related operating expenses but did not change operating income. The impact of these changes on reported segment revenues was immaterial and prior year segment revenues have not been revised.