Variable Interest Entities - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2014 Investment Entity	Jul. 31, 2014 VIE Assets Investment
Variable Interest Entity or Potential VIE, Information Unavailability, Disclosures [Abstract]
Number of identified consolidated variable interest entities		2
Identified investments		6
Investments with no equity at risk		2
Number of additional entities	4
Number of assets identified as variable interests in variable interest entities		2
Investments lacking the right to receive returns	1