Basis of Presentation - Additional Information (Detail)	Dec. 31, 2014	Dec. 31, 2013
Basis of Presentation Disclosure [Abstract]
Ownership interest of sole general partner	96.20%	96.00%
Ownership interest of limited partners	3.80%	4.00%

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

No definition available.

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