Business Segment Information - Financial Information Regarding Company's Operations by Geographic Area (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	$ 1,504,952	$ 1,581,368	$ 2,916,322	$ 3,042,216
Total revenues	1,504,952	1,581,368	2,916,322	3,042,216
Net revenues	453,651	472,561	900,222	926,476
Operating income	132,403	152,275	257,674	299,505
Identifiable assets at quarter end	2,992,372	2,878,004	2,992,372	2,878,004	2,866,827
Capital expenditures	9,814	17,110	26,902	38,235
Depreciation and amortization	9,670	9,257	19,215	18,431
Equity	2,050,057	1,879,150	2,050,057	1,879,150	2,010,069	1,748,154
United States
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	379,126	390,806	756,428	767,911
Transfers between geographic areas	22,504	25,973	44,712	49,938
Total revenues	401,630	416,779	801,140	817,849
Net revenues	182,291	181,603	363,766	359,537
Operating income	49,193	57,752	94,718	111,486
Identifiable assets at quarter end	1,597,543	1,411,881	1,597,543	1,411,881
Capital expenditures	5,236	3,350	14,995	7,380
Depreciation and amortization	5,756	4,926	11,378	9,911
Equity	1,295,963	1,123,482	1,295,963	1,123,482
Other North America
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	49,802	47,816	99,756	91,663
Transfers between geographic areas	2,466	2,783	4,931	5,465
Total revenues	52,268	50,599	104,687	97,128
Net revenues	25,115	21,581	47,357	42,282
Operating income	8,085	5,761	14,454	11,550
Identifiable assets at quarter end	93,374	91,678	93,374	91,678
Capital expenditures	153	448	329	608
Depreciation and amortization	181	277	368	580
Equity	51,248	52,814	51,248	52,814
Latin America
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	21,366	21,136	40,635	41,469
Transfers between geographic areas	4,791	5,220	9,870	10,841
Total revenues	26,157	26,356	50,505	52,310
Net revenues	14,724	15,157	29,559	30,260
Operating income	4,118	4,486	8,880	9,249
Identifiable assets at quarter end	52,019	58,396	52,019	58,396
Capital expenditures	400	144	655	300
Depreciation and amortization	207	264	424	533
Equity	31,903	33,784	31,903	33,784
Asia Pacific
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	780,858	816,350	1,468,928	1,544,480
Transfers between geographic areas	11,038	10,170	22,010	19,353
Total revenues	791,896	826,520	1,490,938	1,563,833
Net revenues	135,908	150,616	267,722	292,104
Operating income	51,768	61,542	99,006	120,980
Identifiable assets at quarter end	687,586	678,668	687,586	678,668
Capital expenditures	2,602	4,622	7,889	9,334
Depreciation and amortization	1,645	1,847	3,269	3,816
Equity	462,123	420,962	462,123	420,962
Europe And Africa
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	202,301	229,724	408,572	443,335
Transfers between geographic areas	9,603	11,355	19,070	22,062
Total revenues	211,904	241,079	427,642	465,397
Net revenues	71,497	78,828	143,030	152,753
Operating income	12,951	16,877	27,198	34,584
Identifiable assets at quarter end	412,752	479,852	412,752	479,852
Capital expenditures	1,111	7,881	2,053	19,587
Depreciation and amortization	1,430	1,416	2,834	2,526
Equity	144,659	184,252	144,659	184,252
Middle East And India
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	71,499	75,536	142,003	153,358
Transfers between geographic areas	4,670	4,500	9,321	8,709
Total revenues	76,169	80,036	151,324	162,067
Net revenues	24,116	24,776	48,788	49,540
Operating income	6,288	5,857	13,418	11,656
Identifiable assets at quarter end	152,754	155,503	152,754	155,503
Capital expenditures	312	665	981	1,026
Depreciation and amortization	451	527	942	1,065
Equity	94,892	94,447	94,892	94,447
Eliminations
Segment Reporting Information [Line Items]
Transfers between geographic areas	(55,072)	(60,001)	(109,914)	(116,368)
Total revenues	(55,072)	(60,001)	(109,914)	(116,368)
Identifiable assets at quarter end	(3,656)	2,026	(3,656)	2,026
Equity	$ (30,731)	$ (30,591)	$ (30,731)	$ (30,591)