Significant Accounting Policies (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Revenues and expenses under collaborative arrangement
ETF advisory fee revenue	$ 20,230	$ 16,514	$ 39,205	$ 30,787
Expenses:
Fund management and administration	5,567	5,736	11,006	9,898
Marketing and advertising	1,548	1,357	2,874	2,329
Sales and business development	842	913	1,702	1,658
Third party expenses	20,264	16,027	38,319	30,405
Net profit	129	689	1,244	844
Third party sharing arrangements [Member]
Revenues and expenses under collaborative arrangement
ETF advisory fee revenue	2,733	3,304	5,523	5,771
Expenses:
Fund management and administration	335	366	676	692
Marketing and advertising	9	167	19	348
Sales and business development	6	27	10	46
Third party expenses	350	560	705	1,086
Net profit	2,383	2,744	4,818	4,685
sharing	$ 1,147	$ 1,372	$ 2,342	$ 2,342