Annual report pursuant to Section 13 and 15(d)

Accumulated Other Comprehensive Income (Loss) - Summary of Changes in Accumulated Other Comprehensive Income (Loss) (Detail)

v3.8.0.1
Accumulated Other Comprehensive Income (Loss) - Summary of Changes in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Beginning Balance $ 725,164 $ 729,048 $ 666,718
Other comprehensive income (loss) before reclassifications 1,452    
Amounts reclassified out of accumulated other comprehensive income (loss) 2,117    
Other comprehensive income (loss) 3,569 3,370 792
Ending Balance 786,760 725,164 729,048
Gains and Losses on Cash Flow Hedges [Member]      
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Beginning Balance (2,085)    
Other comprehensive income (loss) before reclassifications 1,718    
Amounts reclassified out of accumulated other comprehensive income (loss) 2,117    
Other comprehensive income (loss) 3,835    
Ending Balance 1,750 (2,085)  
Defined Benefit Pension Plan [Member]      
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Beginning Balance (177)    
Other comprehensive income (loss) before reclassifications (266)    
Other comprehensive income (loss) (266)    
Ending Balance (443) (177)  
Accumulated Other Comprehensive Income (Loss) [Member]      
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Beginning Balance (2,262) (5,632) (6,424)
Ending Balance $ 1,307 $ (2,262) $ (5,632)