Summary of Significant Accounting Policies - Additional Information (Detail)	Sep. 30, 2014	Dec. 31, 2013	Oct. 07, 2013
Accounting Policies [Abstract]
Percentage of common membership units in subsidiaries	39.53%	39.56%	39.56%

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

No definition available.

Name:	us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant