Consolidated Statements of Comprehensive Income (unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Statement [Abstract]
Revenue	$ 1,106,802	$ 949,491	$ 2,952,173	$ 2,684,126
Operating expenses:
Compensation and benefits	699,031	622,360	1,897,351	1,752,804
Operating, administrative and other	296,012	235,370	808,118	701,731
Depreciation and amortization	19,742	19,089	58,996	58,710
Restructuring and acquistion charges	4,919	6,820	14,689	32,376
Total operating expenses	1,019,704	883,639	2,779,154	2,545,621
Operating income	87,098	65,852	173,019	138,505
Interest expense, net of interest income	(9,631)	(9,952)	(26,603)	(24,837)
Equity in earnings (losses) from real estate ventures	6,574	10,698	21,132	22,500
Income before income taxes and noncontrolling interest	84,041	66,598	167,548	136,168
Provision for income taxes	20,925	16,916	41,719	34,587
Net income	63,116	49,682	125,829	101,581
Net income attributable to noncontrolling interest	259	169	3,286	603
Net income attributable to the Company	62,857	49,513	122,543	100,978
Dividends on unvested common stock, net of tax benefit	0	0	241	253
Net income attributable to common shareholders	62,857	49,513	122,302	100,725
Basic earnings per common share (in dollars per share)	$ 1.42	$ 1.12	$ 2.77	$ 2.30
Basic weighted average shares outstanding (in shares)	44,407,468	44,015,922	44,197,610	43,780,819
Diluted earnings per common share (in dollars per share)	$ 1.39	$ 1.10	$ 2.71	$ 2.25
Diluted weighted average shares outstanding (in shares)	45,063,360	44,826,502	45,070,603	44,755,817
Other comprehensive income (loss):
Net income attributable to the Company	62,857	49,513	122,543	100,978
Foreign currency translation adjustments	42,396	54,924	(45,357)	48,591
Comprehensive income (loss) attributable to the Company	$ 105,253	$ 104,437	$ 77,186	$ 149,569