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, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	$ 1,531,664	$ 1,606,368	$ 4,447,986	$ 4,648,584
Total revenues	1,531,664	1,606,368	4,447,986	4,648,584
Net revenues	465,138	493,846	1,365,360	1,420,322
Operating income	145,099	163,758	402,773	463,263
Identifiable assets at quarter end	3,032,187	2,883,169	3,032,187	2,883,169	2,866,827
Capital expenditures	10,170	20,619	37,072	58,854
Depreciation and amortization	10,030	9,199	29,245	27,630
Equity	2,095,699	1,962,058	2,095,699	1,962,058	2,010,069	1,748,154
United States
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	383,830	388,736	1,140,258	1,156,647
Transfers between geographic areas	24,423	27,161	69,135	77,099
Total revenues	408,253	415,897	1,209,393	1,233,746
Net revenues	187,737	189,381	551,503	548,918
Operating income	56,096	57,564	150,814	169,050
Identifiable assets at quarter end	1,570,615	1,509,393	1,570,615	1,509,393
Capital expenditures	5,681	7,435	20,676	14,815
Depreciation and amortization	5,942	4,904	17,320	14,815
Equity	1,281,250	1,242,594	1,281,250	1,242,594
Other North America
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	50,208	49,341	149,964	141,004
Transfers between geographic areas	2,677	2,989	7,608	8,454
Total revenues	52,885	52,330	157,572	149,458
Net revenues	23,412	23,783	70,769	66,065
Operating income	6,886	7,345	21,340	18,895
Identifiable assets at quarter end	102,020	87,554	102,020	87,554
Capital expenditures	222	315	551	923
Depreciation and amortization	188	250	556	830
Equity	58,471	49,134	58,471	49,134
Latin America
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	20,815	21,353	61,450	62,822
Transfers between geographic areas	4,140	5,025	14,010	15,866
Total revenues	24,955	26,378	75,460	78,688
Net revenues	13,978	15,035	43,537	45,295
Operating income	4,239	4,846	13,119	14,095
Identifiable assets at quarter end	58,687	52,058	58,687	52,058
Capital expenditures	405	162	1,060	462
Depreciation and amortization	220	240	644	773
Equity	33,444	27,258	33,444	27,258
Asia Pacific
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	804,855	839,069	2,273,783	2,383,549
Transfers between geographic areas	10,676	10,500	32,686	29,853
Total revenues	815,531	849,569	2,306,469	2,413,402
Net revenues	146,992	162,785	414,714	454,889
Operating income	59,620	69,001	158,626	189,981
Identifiable assets at quarter end	714,982	667,421	714,982	667,421
Capital expenditures	1,934	7,201	9,823	16,535
Depreciation and amortization	1,691	1,822	4,960	5,638
Equity	499,590	435,466	499,590	435,466
Europe And Africa
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	198,124	229,776	606,696	673,111
Transfers between geographic areas	9,624	10,727	28,694	32,789
Total revenues	207,748	240,503	635,390	705,900
Net revenues	69,841	77,768	212,871	230,521
Operating income	13,312	18,616	40,510	53,200
Identifiable assets at quarter end	423,488	414,991	423,488	414,991
Capital expenditures	1,476	4,981	3,529	24,568
Depreciation and amortization	1,555	1,488	4,389	4,014
Equity	158,939	146,652	158,939	146,652
Middle East And India
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	73,832	78,093	215,835	231,451
Transfers between geographic areas	4,507	4,596	13,828	13,305
Total revenues	78,339	82,689	229,663	244,756
Net revenues	23,178	25,094	71,966	74,634
Operating income	4,946	6,386	18,364	18,042
Identifiable assets at quarter end	162,225	149,253	162,225	149,253
Capital expenditures	452	525	1,433	1,551
Depreciation and amortization	434	495	1,376	1,560
Equity	96,621	92,668	96,621	92,668
Eliminations
Segment Reporting Information [Line Items]
Transfers between geographic areas	(56,047)	(60,998)	(165,961)	(177,366)
Total revenues	(56,047)	(60,998)	(165,961)	(177,366)
Identifiable assets at quarter end	170	2,499	170	2,499
Equity	$ (32,616)	$ (31,714)	$ (32,616)	$ (31,714)