Annual report pursuant to Section 13 and 15(d)

Retirement Plans and Related Post Retirement Benefits - Summarizes the Components of the Net Periodic Cost (Detail)

v3.3.1.900
Retirement Plans and Related Post Retirement Benefits - Summarizes the Components of the Net Periodic Cost (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
SERP      
Net Periodic Cost      
Service cost — benefits earned during period $ 194 $ 247 $ 295
Interest cost 843 721 624
Amortization of prior service cost 495 495 495
Amortization of (gains) losses 449 108 128
Net periodic cost 1,981 1,571 1,542
SERP Medical      
Net Periodic Cost      
Service cost — benefits earned during period 6 3 3
Interest cost 39 31 24
Amortization of prior service cost 26 25 25
Amortization of (gains) losses 26 0 0
Net periodic cost $ 97 $ 59 $ 52