Annual report pursuant to Section 13 and 15(d)

Intangible Assets and Goodwill - Additional Information (Detail)

v3.3.1.900
Intangible Assets and Goodwill - Additional Information (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Schedule Of Goodwill And Intangible Assets [Line Items]      
Goodwill recorded $ 4,000    
Amortizable intangible assets 5,000    
Net intangible assets 26,930 $ 23,058  
Future amortization expenses, 2017 1,000    
Future amortization expenses, 2018 1,000    
Future amortization expenses, 2019 1,000    
Future amortization expenses, 2020 1,000    
Future amortization expenses, 2021 1,000    
Non Real Estate [Member]      
Schedule Of Goodwill And Intangible Assets [Line Items]      
Net intangible assets 1,000 2,000  
Future amortization expenses, 2016 200    
Future amortization expenses, 2017 200    
Future amortization expenses, 2018 200    
Future amortization expenses, 2019 200    
Future amortization expenses, 2020 200    
Future amortization expenses, 2021 200    
Intangible amortization expense $ 200 200 $ 300
American Wind Capital Company, LLC ("AWCC") [Member]      
Schedule Of Goodwill And Intangible Assets [Line Items]      
Goodwill recorded   $ 2,000