Consolidated Statements of Income (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Revenues:
Investment management fees	$ 133,494	$ 111,159	$ 404,123	$ 333,874
Underwriting and distribution fees	131,001	114,071	401,118	341,752
Shareholder service fees	33,254	29,577	99,027	88,014
Total	297,749	254,807	904,268	763,640
Operating expenses:
Underwriting and distribution	151,936	132,857	461,159	400,229
Compensation and related costs (including share-based compensation of $11,662, $10,944, $34,490 and $30,049, respectively)	37,052	36,164	119,619	103,444
General and administrative	22,491	16,022	59,622	48,417
Subadvisory fees	7,291	6,481	23,684	20,441
Depreciation	3,980	3,526	11,426	10,457
Total	222,750	195,050	675,510	582,988
Operating income	74,999	59,757	228,758	180,652
Investment and other income (loss)	(4,365)	3,933	(910)	3,239
Interest expense	(2,838)	(3,128)	(8,573)	(9,797)
Income before provision for income taxes	67,796	60,562	219,275	174,094
Provision for income taxes	27,962	20,029	83,838	63,500
Net income	$ 39,834	$ 40,533	$ 135,437	$ 110,594
Net income per share:
Basic (in dollars per share)	$ 0.46	$ 0.47	$ 1.58	$ 1.29
Diluted (in dollars per share)	$ 0.46	$ 0.47	$ 1.58	$ 1.29
Weighted average shares outstanding:
Basic (in shares)	85,776	85,438	85,951	85,683
Diluted (in shares)	85,782	85,448	85,964	85,715