Basis of Presentation - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2013
Accounting Policies [Abstract]
Economic interest in unconsolidated investments in voting rights entities, minimum	20.00%
Economic interest in unconsolidated investments in voting rights entities, maximum	50.00%
Economic interest in unconsolidated investments in voting rights entities, Ownership less than	20.00%