ETF shareholder proxy solicitation (Details) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2012
ETF Shareholder Proxy Solicitation (Textual) [Abstract]
Percentage of common stock own by beneficial owner		25.30%
Reduced percentage of common stock own by beneficial owner due to sell or transfer		25.00%
ETF shareholder proxy	$ 3,198,000	$ 3,264,000
Maximum [Member]
ETF Shareholder Proxy Solicitation (Textual) [Abstract]
ETF shareholder proxy additional expenses		300,000
Minimum [Member]
ETF Shareholder Proxy Solicitation (Textual) [Abstract]
ETF shareholder proxy additional expenses		$ 200,000