Organization and Description of Business - Additional Information (Detail) (USD $) In Billions, unless otherwise specified	1 Months Ended	6 Months Ended
Jun. 30, 2006 Fund	Jun. 30, 2013 Fund
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Number of ETF launched by the company	20
Number of ETF had by Company		50
Amount of assets under management		$ 29.0

The aggregate costs related to asset management during the reporting period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.2(d))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Name:	us-gaap_AssetManagementCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration