Related Party Transactions - Allocated Costs Included in Combined Statement of Operations (Detail) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2014
Sep. 30, 2013
Sep. 30, 2014
Sep. 30, 2013
Related Party Transactions [Abstract]        
Project expense   $ 768   $ 1,992
Related party general and administrative 1,492 3,607 4,155 8,968
Related party income (664)   (1,736)  
Other income, net   (17)   (551)
Net expenses $ 828 $ 4,358 $ 2,419 $ 10,409