Business Segment Information - Financial Information Regarding Company's Operations by Geographic Area (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012		Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Total revenues	$ 1,535,089		$ 1,531,664		$ 4,446,027		$ 4,447,986
Net revenues	482,025	[1]	465,138	[1]	1,396,410	[1]	1,365,360	[1]
Operating income	146,313		145,099		418,410		402,773
Identifiable assets at period end	3,098,563		3,032,187		3,098,563		3,032,187		2,954,125
Capital expenditures	15,482		10,170		42,691		37,072
Depreciation and amortization	12,629		10,030		35,581		29,245
Equity	2,180,730		2,095,699		2,180,730		2,095,699		2,032,570	2,010,069
United States Segment
Segment Reporting Information [Line Items]
Total revenues	394,046		383,830		1,158,569		1,140,258
Net revenues	196,389	[1]	187,737	[1]	564,895	[1]	551,503	[1]
Operating income	55,627		56,096		161,290		150,814
Identifiable assets at period end	1,694,366		1,570,615		1,694,366		1,570,615
Capital expenditures	12,463		5,681		22,196		20,676
Depreciation and amortization	7,608		5,942		21,641		17,320
Equity	1,423,598		1,281,250		1,423,598		1,281,250
Other North America Segment
Segment Reporting Information [Line Items]
Total revenues	52,962		50,208		161,317		149,964
Net revenues	26,255	[1]	23,412	[1]	75,476	[1]	70,769	[1]
Operating income	8,524		6,886		23,023		21,340
Identifiable assets at period end	102,713		102,020		102,713		102,020
Capital expenditures	639		222		1,534		551
Depreciation and amortization	211		188		615		556
Equity	63,351		58,471		63,351		58,471
Latin America Segment
Segment Reporting Information [Line Items]
Total revenues	22,136		20,815		63,421		61,450
Net revenues	15,627	[1]	13,978	[1]	45,560	[1]	43,537	[1]
Operating income	5,317		4,239		14,007		13,119
Identifiable assets at period end	52,785		58,687		52,785		58,687
Capital expenditures	147		405		551		1,060
Depreciation and amortization	210		220		680		644
Equity	30,637		33,444		30,637		33,444
Asia Pacific Segment
Segment Reporting Information [Line Items]
Total revenues	777,711		804,855		2,221,033		2,273,783
Net revenues	147,343	[1]	146,992	[1]	424,235	[1]	414,714	[1]
Operating income	57,975		59,620		165,640		158,626
Identifiable assets at period end	663,584		714,982		663,584		714,982
Capital expenditures	1,250		1,934		14,858		9,823
Depreciation and amortization	2,343		1,691		6,314		4,960
Equity	439,719		499,590		439,719		499,590
Europe And Africa Segment
Segment Reporting Information [Line Items]
Total revenues	212,482		198,124		620,964		606,696
Net revenues	70,924	[1]	69,841	[1]	212,555	[1]	212,871	[1]
Operating income	11,894		13,312		35,433		40,510
Identifiable assets at period end	438,711		423,488		438,711		423,488
Capital expenditures	703		1,476		2,464		3,529
Depreciation and amortization	1,534		1,555		4,713		4,389
Equity	181,134		158,939		181,134		158,939
Middle East And India Segment
Segment Reporting Information [Line Items]
Total revenues	75,752		73,832		220,723		215,835
Net revenues	25,487	[1]	23,178	[1]	73,689	[1]	71,966	[1]
Operating income	6,976		4,946		19,017		18,364
Identifiable assets at period end	142,843		162,225		142,843		162,225
Capital expenditures	280		452		1,088		1,433
Depreciation and amortization	723		434		1,618		1,376
Equity	75,444		96,621		75,444		96,621
Operating Segments | United States Segment
Segment Reporting Information [Line Items]
Total revenues	416,111		408,253		1,223,877		1,209,393
Operating Segments | Other North America Segment
Segment Reporting Information [Line Items]
Total revenues	55,873		52,885		169,288		157,572
Operating Segments | Latin America Segment
Segment Reporting Information [Line Items]
Total revenues	27,779		24,955		79,554		75,460
Operating Segments | Asia Pacific Segment
Segment Reporting Information [Line Items]
Total revenues	789,792		815,531		2,255,349		2,306,469
Operating Segments | Europe And Africa Segment
Segment Reporting Information [Line Items]
Total revenues	221,840		207,748		648,391		635,390
Operating Segments | Middle East And India Segment
Segment Reporting Information [Line Items]
Total revenues	80,225		78,339		234,082		229,663
Intersegment Eliminations
Segment Reporting Information [Line Items]
Total revenues	(56,531)		(56,047)		(164,514)		(165,961)
Identifiable assets at period end	3,561		170		3,561		170
Equity	(33,153)		(32,616)		(33,153)		(32,616)
Intersegment Eliminations | United States Segment
Segment Reporting Information [Line Items]
Total revenues	(22,065)		(24,423)		(65,308)		(69,135)
Intersegment Eliminations | Other North America Segment
Segment Reporting Information [Line Items]
Total revenues	(2,911)		(2,677)		(7,971)		(7,608)
Intersegment Eliminations | Latin America Segment
Segment Reporting Information [Line Items]
Total revenues	(5,643)		(4,140)		(16,133)		(14,010)
Intersegment Eliminations | Asia Pacific Segment
Segment Reporting Information [Line Items]
Total revenues	(12,081)		(10,676)		(34,316)		(32,686)
Intersegment Eliminations | Europe And Africa Segment
Segment Reporting Information [Line Items]
Total revenues	(9,358)		(9,624)		(27,427)		(28,694)
Intersegment Eliminations | Middle East And India Segment
Segment Reporting Information [Line Items]
Total revenues	$ (4,473)		$ (4,507)		$ (13,359)		$ (13,828)

[1] Net revenues are a non-GAAP measure calculated as revenues less directly related operations 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.