Business Segment Information - Financial Information Regarding Company's Operations by Geographic Area (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	$ 1,411,370	$ 1,460,848
Total revenues	1,411,370	1,460,848
Net revenues	446,571	453,915
Operating income	125,271	147,230
Identifiable assets at quarter end	3,001,223	2,836,732	2,866,827
Capital expenditures	17,088	21,125
Depreciation and amortization	9,545	9,174
Equity	2,102,034	1,849,120	2,010,069	1,748,154
United States
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	377,302	377,106
Transfers between geographic areas	22,208	23,965
Total revenues	399,510	401,071
Net revenues	181,475	177,934
Operating income	45,525	53,734
Identifiable assets at quarter end	1,590,900	1,427,414
Capital expenditures	9,759	4,030
Depreciation and amortization	5,622	4,985
Equity	1,315,321	1,124,913
Other North America
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	49,954	43,846
Transfers between geographic areas	2,465	2,682
Total revenues	52,419	46,528
Net revenues	22,242	20,701
Operating income	6,369	5,789
Identifiable assets at quarter end	96,312	86,371
Capital expenditures	176	160
Depreciation and amortization	187	303
Equity	56,341	47,793
Latin America
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	19,269	20,332
Transfers between geographic areas	5,079	5,621
Total revenues	24,348	25,953
Net revenues	14,835	15,103
Operating income	4,762	4,763
Identifiable assets at quarter end	52,214	57,960
Capital expenditures	255	156
Depreciation and amortization	217	269
Equity	31,060	30,981
Asia Pacific
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	688,070	728,130
Transfers between geographic areas	10,972	9,183
Total revenues	699,042	737,313
Net revenues	131,814	141,487
Operating income	47,238	59,438
Identifiable assets at quarter end	708,528	659,352
Capital expenditures	5,287	4,712
Depreciation and amortization	1,624	1,969
Equity	471,498	407,053
Europe And Africa
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	206,271	213,612
Transfers between geographic areas	9,467	10,707
Total revenues	215,738	224,319
Net revenues	71,533	73,926
Operating income	14,247	17,707
Identifiable assets at quarter end	404,839	452,675
Capital expenditures	942	11,706
Depreciation and amortization	1,404	1,110
Equity	164,165	181,245
Middle East And India
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	70,504	77,822
Transfers between geographic areas	4,651	4,209
Total revenues	75,155	82,031
Net revenues	24,672	24,764
Operating income	7,130	5,799
Identifiable assets at quarter end	149,416	153,236
Capital expenditures	669	361
Depreciation and amortization	491	538
Equity	93,282	89,422
Eliminations
Segment Reporting Information [Line Items]
Transfers between geographic areas	(54,842)	(56,367)
Total revenues	(54,842)	(56,367)
Identifiable assets at quarter end	(986)	(276)
Equity	$ (29,633)	$ (32,287)