Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Operating Revenues:
Total revenues	$ 74,775	$ 56,242	$ 133,679	$ 109,609
Operating Expenses:
Compensation and benefits	19,301	18,421	38,133	36,295
Fund management and administration	14,621	10,112	25,533	19,712
Marketing and advertising	3,778	3,825	6,973	7,362
Sales and business development	4,503	3,389	8,316	6,351
Contractual gold payments (Note 11)	2,715		2,715
Professional and consulting fees	1,560	1,221	3,196	2,779
Occupancy, communications and equipment	1,574	1,371	2,937	2,724
Depreciation and amortization	337	352	692	689
Third-party distribution fees	1,666	670	3,391	1,602
Acquisition-related costs (Note 3)	7,928		9,990
Other	2,261	1,842	4,051	3,466
Total expenses	60,244	41,203	105,927	80,980
Operating income	14,531	15,039	27,752	28,629
Other Income/(Expenses):
Interest expense	(2,356)		(2,356)
Gain on revaluation of deferred consideration - gold payments (Note 11)	9,898		9,898
Interest income	612	641	1,574	1,225
Settlement gain		6,909		6,909
Other gains and losses, net	(501)	(364)	(762)	284
Income before taxes	22,184	22,225	36,106	37,047
Income tax expense	5,460	10,120	9,958	18,062
Net income	$ 16,724	$ 12,105	$ 26,148	$ 18,985
Net income per share-basic	$ 0.10	$ 0.09	$ 0.17	$ 0.14
Net income per share-diluted	$ 0.10	$ 0.09	$ 0.17	$ 0.14
Weighted-average common shares-basic	149,056	134,557	142,230	134,472
Weighted-average common shares-diluted	163,346	135,574	149,979	135,613
Cash dividends declared per common share	$ 0.03	$ 0.08	$ 0.06	$ 0.16
Advisory Fees [Member]
Operating Revenues:
Total revenues	$ 73,778	$ 55,856	$ 132,234	$ 108,884
Other Income [Member]
Operating Revenues:
Total revenues	$ 997	$ 386	$ 1,445	$ 725