Segments (Summarized Financial Information By Segment) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Segment Reporting Information [Line Items]
Revenue	$ 2,005,846	$ 1,557,147	$ 1,601,117	$ 1,349,989	$ 1,763,625	$ 1,534,463	$ 1,422,218	$ 1,185,105	$ 6,514,099		$ 5,905,411		$ 5,115,316
Depreciation and amortization									169,645		115,719		108,381
Equity income (loss) from unconsolidated subsidiaries									60,729		104,776		26,561
EBITDA									861,621		693,261		647,467
Global Investment Management [Member]
Segment Reporting Information [Line Items]
Revenue									482,589		290,065		215,631
Depreciation and amortization									51,290		21,271		13,968
Equity income (loss) from unconsolidated subsidiaries									(2,533)		(1,044)		(8,039)
EBITDA									96,359	[1]	(14,772)	[1]	48,556	[1]
Development Services [Member]
Segment Reporting Information [Line Items]
Revenue									78,849		76,343		75,664
Depreciation and amortization									9,841		11,611		15,812
Equity income (loss) from unconsolidated subsidiaries									49,167		89,875		22,047
EBITDA									51,684	[2]	76,113	[2]	48,656	[2]
Americas [Member]
Segment Reporting Information [Line Items]
Revenue									4,103,602		3,673,681		3,217,543
Depreciation and amortization									82,841		62,238		60,663
Equity income (loss) from unconsolidated subsidiaries									12,890		15,162		11,708
EBITDA									578,649		462,167		389,991
EMEA [Member]
Segment Reporting Information [Line Items]
Revenue									1,031,818		1,076,568		936,581
Depreciation and amortization									14,198		10,945		9,519
Equity income (loss) from unconsolidated subsidiaries									1,205		778		848
EBITDA									54,299		87,527		89,407
Asia Pacific [Member]
Segment Reporting Information [Line Items]
Revenue									817,241		788,754		669,897
Depreciation and amortization									11,475		9,654		8,419
Equity income (loss) from unconsolidated subsidiaries											5		(3)
EBITDA									$ 80,630		$ 82,226		$ 70,857

[1] Includes EBITDA related to discontinued operations of $0.5 million and $4.0 million for the years ended December 31, 2012 and 2011, respectively.

[2] Includes EBITDA related to discontinued operations of $5.1 million, $10.1 million and $16.4 million for the years ended December 31, 2012, 2011 and 2010, respectively.