Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Revenues:
Investment management fees	$ 134,213	$ 138,985	$ 269,113	$ 270,629
Underwriting and distribution fees	139,944	137,354	277,434	270,117
Shareholder service fees	34,051	33,606	68,279	65,773
Total	308,208	309,945	614,826	606,519
Operating expenses:
Underwriting and distribution	163,032	157,219	322,507	309,223
Compensation and related costs (including share-based compensation of $12,293, $12,960, $24,565 and $22,828, respectively)	42,973	42,092	88,376	82,567
General and administrative	25,095	19,500	44,419	37,131
Subadvisory fees	5,208	8,313	11,479	16,393
Depreciation	3,428	3,842	6,900	7,446
Total	239,736	230,966	473,681	452,760
Operating income	68,472	78,979	141,145	153,759
Investment and other income	1,272	2,452	5,328	3,455
Interest expense	(2,825)	(2,835)	(5,652)	(5,735)
Income before provision for income taxes	66,919	78,596	140,821	151,479
Provision for income taxes	25,201	28,626	51,716	55,876
Net income	$ 41,718	$ 49,970	$ 89,105	$ 95,603
Net income per share:
Basic (in dollars per share)	$ 0.48	$ 0.58	$ 1.04	$ 1.11
Diluted (in dollars per share)	$ 0.48	$ 0.58	$ 1.04	$ 1.11
Weighted average shares outstanding:
Basic (in shares)	86,093	86,264	85,848	86,040
Diluted (in shares)	86,095	86,275	85,851	86,057