Business Segment Information - Financial Information Regarding Company's Operations by Geographic Area (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Total revenues		$ 1,562,394	$ 1,651,332	$ 4,456,030	$ 5,020,411
Net revenues	[1]	545,259	569,981	1,615,445	1,651,608
Operating income		167,263	191,893	497,953	543,492
Identifiable assets at period end		2,813,797	2,827,018	2,813,797	2,827,018	$ 2,582,438
Capital expenditures		12,659	9,546	39,973	31,903
Depreciation and amortization		11,882	11,475	34,853	34,424
Equity		1,853,933	1,842,192	1,853,933	1,842,192	$ 1,694,676	$ 1,871,608
United States Segment
Segment Reporting Information [Line Items]
Total revenues		423,362	441,097	1,248,923	1,334,900
Other North America Segment
Segment Reporting Information [Line Items]
Total revenues		56,747	56,818	165,527	170,351
Latin America Segment
Segment Reporting Information [Line Items]
Total revenues		21,592	24,681	62,825	73,076
North Asia Segment
Segment Reporting Information [Line Items]
Total revenues		590,622	648,096	1,605,343	1,943,441
South Asia Segment
Segment Reporting Information [Line Items]
Total revenues		154,156	158,011	442,464	524,254
Europe Segment
Segment Reporting Information [Line Items]
Total revenues		228,256	234,334	680,035	716,373
Middle East Africa And India Segment
Segment Reporting Information [Line Items]
Total revenues		87,659	88,295	250,913	258,016
Geography Eliminations | United States Segment
Segment Reporting Information [Line Items]
Total revenues		24,610	29,168	79,617	89,329
Geography Eliminations | Other North America Segment
Segment Reporting Information [Line Items]
Total revenues		2,770	3,492	8,141	9,991
Geography Eliminations | Latin America Segment
Segment Reporting Information [Line Items]
Total revenues		3,724	4,991	11,512	15,171
Geography Eliminations | North Asia Segment
Segment Reporting Information [Line Items]
Total revenues		5,368	5,206	15,849	16,330
Geography Eliminations | South Asia Segment
Segment Reporting Information [Line Items]
Total revenues		6,206	6,289	18,338	18,677
Geography Eliminations | Europe Segment
Segment Reporting Information [Line Items]
Total revenues		9,938	11,125	30,396	31,478
Geography Eliminations | Middle East Africa And India Segment
Segment Reporting Information [Line Items]
Total revenues		5,551	5,459	16,452	15,638
Operating Segments | United States Segment
Segment Reporting Information [Line Items]
Total revenues		447,972	470,265	1,328,540	1,424,229
Net revenues	[1]	229,773	232,912	683,331	681,868
Operating income		69,457	65,389	184,876	193,117
Identifiable assets at period end		1,429,860	1,385,157	1,429,860	1,385,157
Capital expenditures		8,319	6,196	25,234	20,232
Depreciation and amortization		7,566	7,439	22,264	22,171
Equity		1,145,293	1,144,466	1,145,293	1,144,466
Operating Segments | Other North America Segment
Segment Reporting Information [Line Items]
Total revenues		59,517	60,310	173,668	180,342
Net revenues	[1]	30,211	32,713	88,404	93,967
Operating income		6,200	11,905	23,091	33,433
Identifiable assets at period end		95,390	108,644	95,390	108,644
Capital expenditures		720	658	1,476	2,602
Depreciation and amortization		369	363	1,113	965
Equity		41,542	64,384	41,542	64,384
Operating Segments | Latin America Segment
Segment Reporting Information [Line Items]
Total revenues		25,316	29,672	74,337	88,247
Net revenues	[1]	14,063	17,115	42,264	51,159
Operating income		3,328	5,007	11,016	15,804
Identifiable assets at period end		56,192	56,987	56,192	56,987
Capital expenditures		139	222	941	1,408
Depreciation and amortization		328	268	869	784
Equity		37,765	35,890	37,765	35,890
Operating Segments | North Asia Segment
Segment Reporting Information [Line Items]
Total revenues		595,990	653,302	1,621,192	1,959,771
Net revenues	[1]	124,251	135,488	357,159	377,384
Operating income		59,682	69,690	176,621	187,343
Identifiable assets at period end		480,587	472,189	480,587	472,189
Capital expenditures		739	711	2,502	1,476
Depreciation and amortization		1,404	1,336	4,111	4,114
Equity		293,383	250,362	293,383	250,362
Operating Segments | South Asia Segment
Segment Reporting Information [Line Items]
Total revenues		160,362	164,300	460,802	542,931
Net revenues	[1]	42,711	45,970	128,486	135,114
Operating income		14,045	18,574	48,090	48,594
Identifiable assets at period end		117,333	140,206	117,333	140,206
Capital expenditures		319	291	1,325	1,599
Depreciation and amortization		594	531	1,649	1,609
Equity		87,926	103,457	87,926	103,457
Operating Segments | Europe Segment
Segment Reporting Information [Line Items]
Total revenues		238,194	245,459	710,431	747,851
Net revenues	[1]	74,888	77,250	227,068	229,745
Operating income		7,018	14,188	31,109	44,846
Identifiable assets at period end		388,543	427,053	388,543	427,053
Capital expenditures		2,127	1,223	6,386	3,292
Depreciation and amortization		1,116	1,120	3,402	3,542
Equity		129,989	148,287	129,989	148,287
Operating Segments | Middle East Africa And India Segment
Segment Reporting Information [Line Items]
Total revenues		93,210	93,754	267,365	273,654
Net revenues	[1]	29,363	28,533	88,745	82,371
Operating income		7,534	7,140	23,162	20,355
Identifiable assets at period end		237,104	229,670	237,104	229,670
Capital expenditures		296	245	2,109	1,294
Depreciation and amortization		505	418	1,445	1,239
Equity		150,395	126,321	150,395	126,321
Intersegment Eliminations
Segment Reporting Information [Line Items]
Total revenues		(58,167)	(65,730)	(180,305)	(196,614)
Net revenues	[1]	(1)		(12)
Operating income		(1)		(12)
Identifiable assets at period end		8,788	7,112	8,788	7,112
Equity		$ (32,360)	$ (30,975)	$ (32,360)	$ (30,975)

[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.