Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Revenues:
Investment management fees	$ 148,445	$ 134,900
Underwriting and distribution fees	135,419	121,153
Shareholder service fees	32,691	31,818
Total	316,555	287,871
Operating expenses:
Underwriting and distribution	161,571	144,486
Compensation and related costs (including share-based compensation of $11,676 and $11,886, respectively)	48,155	44,158
General and administrative	16,208	17,764
Subadvisory fees	4,484	6,271
Depreciation	3,227	3,359
Total	233,645	216,038
Operating income	82,910	71,833
Investment and other income	4,377	3,949
Interest expense	(2,854)	(2,826)
Income from continuing operations before provision for income taxes	84,433	72,956
Provision for income taxes	30,570	26,119
Income from continuing operations	53,863	46,837
Income from discontinued operations net of tax expense of $397		550
Net income	$ 53,863	$ 47,387
Net income per share, basic and diluted:
Income from continuing operations (in dollars per share)	$ 0.63	$ 0.55
Income from discontinued operations (in dollars per share)	$ 0.00
Net income (in dollars per share)	$ 0.63	$ 0.55
Weighted average shares outstanding:
Basic (in shares)	85,592	85,604
Diluted (in shares)	85,593	85,606