Consolidated Statements of Comprehensive Income (unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Statement [Abstract]
Revenue	$ 1,365,975	$ 1,106,802	$ 3,680,622	$ 2,952,173
Operating expenses:
Compensation and benefits	828,241	699,031	2,226,804	1,897,351
Operating, administrative and other	388,290	296,012	1,141,376	808,118
Depreciation and amortization	22,023	19,742	67,214	58,996
Restructuring and acquisition charges	(37)	4,919	41,379	14,689
Total operating expenses	1,238,517	1,019,704	3,476,773	2,779,154
Operating income	127,458	87,098	203,849	173,019
Interest expense, net of interest income	(7,361)	(9,631)	(21,661)	(26,603)
Equity in earnings from real estate ventures	19,552	6,574	40,945	21,132
Income before income taxes and noncontrolling interest	139,649	84,041	223,133	167,548
Provision for income taxes	34,912	20,925	29,889	41,719
Net income	104,737	63,116	193,244	125,829
Net income attributable to noncontrolling interest	453	259	1,116	3,286
Net income attributable to the Company	104,284	62,857	192,128	122,543
Dividends, Share-based Compensation	0	0	176	241
Net income attributable to common shareholders	104,284	62,857	191,952	122,302
Basic earnings per common share (in dollars per share)	$ 2.33	$ 1.42	$ 4.30	$ 2.77
Basic weighted average shares outstanding (in shares)	44,809,133	44,407,468	44,637,429	44,197,610
Diluted earnings per common share (in dollars per share)	$ 2.30	$ 1.39	$ 4.24	$ 2.71
Diluted weighted average shares outstanding (in shares)	45,290,595	45,063,360	45,241,766	45,070,603
Other comprehensive income:
Net income attributable to the Company	104,284	62,857	192,128	122,543
Foreign currency translation adjustments	(90,589)	42,396	(51,637)	(45,357)
Comprehensive income attributable to the Company	$ 13,695	$ 105,253	$ 140,491	$ 77,186