Financial Information Regarding Company's Operations by Geographic Area (Detail) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010	Dec. 31, 2009
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	$ 1,606,368	$ 1,667,559	$ 4,648,584	$ 4,385,438
Total revenues	1,606,368	1,667,559	4,648,584	4,385,438
Net revenues	493,846	458,743	1,420,322	1,239,424
Operating income	163,758	159,621	463,263	398,658
Identifiable assets at quarter end	2,883,169	2,716,183	2,883,169	2,716,183	2,679,179
Capital expenditures	20,619	10,953	58,854	26,653
Depreciation and amortization	9,199	9,085	27,630	27,590
Equity	1,962,058	1,736,118	1,962,058	1,736,118	1,748,154	1,561,347
United States
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	388,736	361,120	1,156,647	979,675
Transfers between geographic areas	27,161	28,571	77,099	72,743
Total revenues	415,897	389,691	1,233,746	1,052,418
Net revenues	189,381	179,290	548,918	489,231
Operating income	57,564	61,735	169,050	152,425
Identifiable assets at quarter end	1,509,393	1,437,318	1,509,393	1,437,318
Capital expenditures	7,435	5,297	14,815	13,137
Depreciation and amortization	4,904	4,882	14,815	14,753
Equity	1,242,594	1,121,817	1,242,594	1,121,817
Other North America
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	49,341	43,380	141,004	120,667
Transfers between geographic areas	2,989	3,567	8,454	7,722
Total revenues	52,330	46,947	149,458	128,389
Net revenues	23,783	20,911	66,065	56,757
Operating income	7,345	6,846	18,895	16,317
Identifiable assets at quarter end	87,554	78,347	87,554	78,347
Capital expenditures	315	92	923	417
Depreciation and amortization	250	316	830	1,023
Equity	49,134	40,708	49,134	40,708
Latin America
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	21,353	20,400	62,822	55,317
Transfers between geographic areas	5,025	4,190	15,866	12,082
Total revenues	26,378	24,590	78,688	67,399
Net revenues	15,035	13,181	45,295	37,428
Operating income	4,846	3,837	14,095	11,155
Identifiable assets at quarter end	52,058	48,887	52,058	48,887
Capital expenditures	162	354	462	988
Depreciation and amortization	240	223	773	639
Equity	27,258	23,974	27,258	23,974
Asia Pacific
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	839,069	968,858	2,383,549	2,482,116
Transfers between geographic areas	10,500	8,593	29,853	23,861
Total revenues	849,569	977,451	2,413,402	2,505,977
Net revenues	162,785	153,241	454,889	397,678
Operating income	69,001	64,046	189,981	158,938
Identifiable assets at quarter end	667,421	574,216	667,421	574,216
Capital expenditures	7,201	1,853	16,535	3,967
Depreciation and amortization	1,822	1,871	5,638	5,626
Equity	426,164	346,210	426,164	346,210
Europe And Africa
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	229,776	190,350	673,111	525,064
Transfers between geographic areas	10,727	11,045	32,789	29,407
Total revenues	240,503	201,395	705,900	554,471
Net revenues	77,768	68,158	230,521	192,135
Operating income	18,616	17,128	53,200	43,870
Identifiable assets at quarter end	414,991	433,020	414,991	433,020
Capital expenditures	4,981	2,963	24,568	6,415
Depreciation and amortization	1,488	1,184	4,014	3,721
Equity	146,652	155,428	146,652	155,428
Middle East And India
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	78,093	83,451	231,451	222,599
Transfers between geographic areas	4,596	4,448	13,305	11,918
Total revenues	82,689	87,899	244,756	234,517
Net revenues	25,094	23,962	74,634	66,195
Operating income	6,386	6,029	18,042	15,953
Identifiable assets at quarter end	149,253	139,478	149,253	139,478
Capital expenditures	525	394	1,551	1,729
Depreciation and amortization	495	609	1,560	1,828
Equity	92,668	80,774	92,668	80,774
Eliminations
Segment Reporting Information [Line Items]
Transfers between geographic areas	(60,998)	(60,414)	(177,366)	(157,733)
Total revenues	(60,998)	(60,414)	(177,366)	(157,733)
Identifiable assets at quarter end	2,499	4,917	2,499	4,917
Equity	$ (22,412)	$ (32,793)	$ (22,412)	$ (32,793)