Quarterly report pursuant to sections 13 or 15(d)

Notes Receivable from Partners - Additional Information (Detail)

v2.4.0.8
Notes Receivable from Partners - Additional Information (Detail) (Partners [Member], USD $)
In Thousands, unless otherwise specified
6 Months Ended
Jun. 30, 2013
Dec. 31, 2012
Dec. 31, 2011
Jun. 30, 2013
Limited Recourse [Member]
Dec. 31, 2012
Limited Recourse [Member]
Sep. 30, 2009
Limited Recourse [Member]
Aug. 31, 2009
Limited Recourse [Member]
Jan. 31, 2008
Limited Recourse [Member]
Jun. 30, 2013
Full Recourse [Member]
Dec. 31, 2012
Full Recourse [Member]
Related Party Transaction [Line Items]                    
Term of promissory notes receivable In the form of five or six year interest-bearing promissory notes and/or in the form of nine year interest-bearing limited recourse promissory notes                  
Interest rates of promissory notes           2.84% 2.77% 3.53%    
Notes receivable from partners $ 3,023 $ 3,410 $ 6,024 $ 1,953 $ 1,457       $ 1,652 $ 1,371