v3.8.0.1
Interest Rate Swaps - Total Loss Recognized Converting Variable Rates to Fixed Rates and Location of the Loss (Detail) - Interest Rate Swap - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Derivative [Line Items]      
Location of Loss Reclassified from Accumulated Other Comprehensive Income into Income Interest expense Interest expense Interest expense
Amount of Loss Reclassified from Accumulated Other Comprehensive Income into Income $ 5,099 $ 9,322 $ 7,162
Location of Loss Recognized in Income on Derivatives Interest expense Interest expense Interest expense
Amount of Loss Recognized in Income on Derivatives $ 332