Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues:
ETF advisory fees	$ 297,944	$ 182,816	$ 148,594
Other income	998	946	874
Total revenues	298,942	183,762	149,468
Expenses:
Compensation and benefits	73,228	40,995	36,210
Fund management and administration	42,782	34,383	35,076
Marketing and advertising	13,371	11,514	8,309
Sales and business development	9,189	6,221	6,474
Professional and consulting fees	7,067	7,578	2,748
Occupancy, communications, and equipment	4,299	3,578	2,784
Depreciation and amortization	1,006	821	439
Third party sharing arrangements	2,443	594	1,368
Acquisition contingent payment	2,185
Other	6,187	4,530	4,523
Total expenses	161,757	110,214	97,931
Income before taxes	137,185	73,548	51,537
Income tax expense	57,133	12,497
Net income	$ 80,052	$ 61,051	$ 51,537
Net income per share - basic	$ 0.58	$ 0.46	$ 0.41
Net income per share - diluted	$ 0.58	$ 0.44	$ 0.37
Weighted-average common shares - basic	137,242	131,770	126,651
Weighted-average common shares - diluted	138,825	138,551	139,797
Cash dividends declared per common share	$ 0.57	$ 0.08