Subsequent Events - Additional Information (Detail) (USD $)	1 Months Ended
	Aug. 23, 2013
Subsequent Event [Line Items]
Administrative services fees on average daily net assets	$ 10,000
Minimum [Member] | Investor Class Shares [Member]
Subsequent Event [Line Items]
Board of trustees approved an increase to the administrative services fees paid to the Company	0.08%
Minimum [Member] | Institutional Class Shares [Member]
Subsequent Event [Line Items]
Board of trustees approved an increase to the administrative services fees paid to the Company	0.06%
Maximum [Member] | Investor Class Shares [Member]
Subsequent Event [Line Items]
Board of trustees approved an increase to the administrative services fees paid to the Company	0.10%
Maximum [Member] | Institutional Class Shares [Member]
Subsequent Event [Line Items]
Board of trustees approved an increase to the administrative services fees paid to the Company	0.08%