Revenues - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	$ 22,462				$ 22,462
Deferred contract costs	168,090				168,090			$ 0
Contract liabilities	195,035				195,035			$ 0
Revenue from Contract with Customer, Excluding Assessed Tax	2,090,947			$ 1,802,166	5,902,768	$ 5,019,577
Cost of Customs brokerage and other services	1,887,793			1,615,271	5,323,212	4,518,328
Customs brokerage and other services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	671,799			$ 503,616	$ 1,899,741	$ 1,411,270
Prospective Change in Presentation Gross vs. Net | Customs brokerage and other services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	50,000	$ 50,000	$ 50,000
Cost of Customs brokerage and other services	$ 50,000	$ 50,000	$ 50,000
Revenue Accounting Standards Update
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets							$ 22,000
Deferred contract costs							135,000
Contract liabilities							$ 165,000