Business Segment Information - Net Revenues Calculation (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Schedule of Net Revenues Calculation [Line Items]
Total revenues		$ 1,957,559	$ 1,672,279	$ 3,811,821	$ 3,217,411
Expenses [Abstract]
Net revenues	[1]	642,546	563,633	1,278,384	1,091,238
Airfreight services
Schedule of Net Revenues Calculation [Line Items]
Total revenues		801,761	671,868	1,532,988	1,287,413
Expenses [Abstract]
Direct Operating Costs		593,325	499,418	1,106,829	942,822
Ocean freight and ocean services
Schedule of Net Revenues Calculation [Line Items]
Total revenues		530,008	528,585	1,050,891	1,022,344
Expenses [Abstract]
Direct Operating Costs		385,156	385,927	764,574	751,990
Customs brokerage and other services
Schedule of Net Revenues Calculation [Line Items]
Total revenues		625,790	471,826	1,227,942	907,654
Expenses [Abstract]
Direct Operating Costs		$ 336,532	$ 223,301	$ 662,034	$ 431,361

[1] Net revenues are a non-GAAP measure calculated as revenues less directly related operating expenses attributable to the Company's principal services. The Company's management believes that net revenues are a better measure than total revenues when evaluating the Company's operating segment performance since total revenues earned as a freight consolidator include the carriers' charges for carrying the shipment, whereas revenues earned in other capacities include primarily the commissions and fees earned by the Company. Net revenue is one of the Company's primary operational and financial measures and demonstrates the Company's ability to concentrate and leverage purchasing power through effective consolidation of shipments from customers utilizing a variety of transportation carriers and optimal routings.