Employee Benefit Plans - Summary of Accumulated Benefit Obligation in Excess of Plan Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plans [Member]
Accumulated benefit obligation in excess of plan assets [Abstract]
Accumulated benefit obligation	$ 78,859	$ 85,279
Fair value of plan assets	45,713	59,096
SERP [Member]
Accumulated benefit obligation in excess of plan assets [Abstract]
Accumulated benefit obligation	$ 46,428	$ 45,617