Business Segment Information - Financial Information Regarding Company's Operations by Geographic Area (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Total revenues		$ 1,691,553	$ 1,599,141	$ 3,369,079	$ 3,090,786
Net revenues	[1]	552,141	484,714	1,081,627	949,300
Operating income		182,716	142,443	351,599	277,646
Identifiable assets at period end		2,932,375	2,929,940	2,932,375	2,929,940	$ 2,890,905
Capital expenditures		12,912	9,635	22,357	18,395
Depreciation and amortization		11,420	12,417	22,949	24,799
Equity		1,889,733	1,897,137	1,889,733	1,897,137	$ 1,871,608	$ 2,086,331
United States Segment
Segment Reporting Information [Line Items]
Total revenues		449,622	416,454	893,803	817,193
Net revenues	[1]	229,353	200,106	448,956	392,188
Operating income		68,547	59,780	127,728	111,678
Identifiable assets at period end		1,381,755	1,328,312	1,381,755	1,328,312
Capital expenditures		7,711	5,547	14,036	9,475
Depreciation and amortization		7,339	7,879	14,732	15,731
Equity		1,075,703	1,044,386	1,075,703	1,044,386
Other North America Segment
Segment Reporting Information [Line Items]
Total revenues		58,739	55,343	113,533	106,927
Net revenues	[1]	30,576	25,533	61,254	51,694
Operating income		10,437	7,001	21,528	15,376
Identifiable assets at period end		103,613	110,498	103,613	110,498
Capital expenditures		1,656	422	1,944	686
Depreciation and amortization		310	296	602	576
Equity		59,374	72,681	59,374	72,681
Latin America Segment
Segment Reporting Information [Line Items]
Total revenues		24,314	22,003	48,395	42,632
Net revenues	[1]	17,485	16,648	34,044	32,005
Operating income		5,441	4,676	10,797	9,535
Identifiable assets at period end		57,711	57,588	57,711	57,588
Capital expenditures		569	171	1,186	472
Depreciation and amortization		248	227	516	439
Equity		38,447	35,578	38,447	35,578
North Asia Segment
Segment Reporting Information [Line Items]
Total revenues		649,901	623,625	1,295,345	1,192,314
Net revenues	[1]	124,491	97,498	241,896	190,892
Operating income		60,597	39,321	117,653	79,375
Identifiable assets at period end		572,425	587,891	572,425	587,891
Capital expenditures		475	1,383	765	4,043
Depreciation and amortization		1,379	1,476	2,778	2,978
Equity		344,479	356,974	344,479	356,974
South Asia Segment
Segment Reporting Information [Line Items]
Total revenues		184,862	152,570	366,243	293,313
Net revenues	[1]	46,944	40,145	89,144	79,238
Operating income		16,140	11,828	30,020	24,298
Identifiable assets at period end		141,344	153,660	141,344	153,660
Capital expenditures		989	518	1,308	974
Depreciation and amortization		548	620	1,078	1,216
Equity		118,175	122,577	118,175	122,577
Europe Segment
Segment Reporting Information [Line Items]
Total revenues		239,953	250,823	482,039	484,506
Net revenues	[1]	76,607	79,958	152,495	154,289
Operating income		15,587	14,952	30,658	26,594
Identifiable assets at period end		448,475	481,190	448,475	481,190
Capital expenditures		921	1,234	2,069	2,100
Depreciation and amortization		1,176	1,478	2,422	2,985
Equity		166,569	189,296	166,569	189,296
Middle East Africa And India Segment
Segment Reporting Information [Line Items]
Total revenues		84,162	78,323	169,721	153,901
Net revenues	[1]	26,685	24,826	53,838	48,994
Operating income		5,967	4,885	13,215	10,790
Identifiable assets at period end		219,280	205,023	219,280	205,023
Capital expenditures		591	360	1,049	645
Depreciation and amortization		420	441	821	874
Equity		124,564	112,394	124,564	112,394
Operating Segments | United States Segment
Segment Reporting Information [Line Items]
Total revenues		482,108	438,862	953,964	859,612
Operating Segments | Other North America Segment
Segment Reporting Information [Line Items]
Total revenues		62,424	57,930	120,032	111,889
Operating Segments | Latin America Segment
Segment Reporting Information [Line Items]
Total revenues		29,717	27,570	58,575	53,403
Operating Segments | North Asia Segment
Segment Reporting Information [Line Items]
Total revenues		655,328	629,262	1,306,469	1,203,368
Operating Segments | South Asia Segment
Segment Reporting Information [Line Items]
Total revenues		191,335	159,278	378,631	306,571
Operating Segments | Europe Segment
Segment Reporting Information [Line Items]
Total revenues		250,669	260,652	502,392	503,654
Operating Segments | Middle East Africa And India Segment
Segment Reporting Information [Line Items]
Total revenues		89,274	83,248	179,900	163,368
Intersegment Eliminations
Segment Reporting Information [Line Items]
Total revenues		(69,302)	(57,661)	(130,884)	(111,079)
Identifiable assets at period end		7,772	5,778	7,772	5,778
Equity		(37,578)	(36,749)	(37,578)	(36,749)
Intersegment Eliminations | United States Segment
Segment Reporting Information [Line Items]
Total revenues		(32,486)	(22,408)	(60,161)	(42,419)
Intersegment Eliminations | Other North America Segment
Segment Reporting Information [Line Items]
Total revenues		(3,685)	(2,587)	(6,499)	(4,962)
Intersegment Eliminations | Latin America Segment
Segment Reporting Information [Line Items]
Total revenues		(5,403)	(5,567)	(10,180)	(10,771)
Intersegment Eliminations | North Asia Segment
Segment Reporting Information [Line Items]
Total revenues		(5,427)	(5,637)	(11,124)	(11,054)
Intersegment Eliminations | South Asia Segment
Segment Reporting Information [Line Items]
Total revenues		(6,473)	(6,708)	(12,388)	(13,258)
Intersegment Eliminations | Europe Segment
Segment Reporting Information [Line Items]
Total revenues		(10,716)	(9,829)	(20,353)	(19,148)
Intersegment Eliminations | Middle East Africa And India Segment
Segment Reporting Information [Line Items]
Total revenues		$ (5,112)	$ (4,925)	$ (10,179)	$ (9,467)

[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.