Goodwill and Intangible Assets - Summary of Amortization Expense to be Incurred Over Next Four Years on Intangible Assets (Detail)
$ in Thousands
Sep. 30, 2015
USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]  
2015 $ 15,156
2016 13,113
2017 10,956
2018 8,088
2019 $ 6,953