Business Segment Information Business Segment Information - Net Revenues Calculation (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Segment Reporting [Abstract]
Total revenues	$ 1,901,371	$ 1,802,166	$ 1,672,279	$ 1,545,132	$ 1,642,007	$ 1,562,394	$ 1,475,164	$ 1,418,472	$ 6,920,948		$ 6,098,037		$ 6,616,632
Airfreight services									2,126,761		1,752,167		1,987,690
Ocean freight and ocean services									1,543,740		1,378,699		1,648,993
Customs brokerage and other services									931,258		803,135		792,172
Net revenues	$ 628,809	$ 599,142	$ 563,633	$ 527,605	$ 548,591	$ 545,259	$ 553,117	$ 517,069	$ 2,319,189	[1]	$ 2,164,036	[1]	$ 2,187,777	[1]

[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.