Employee Benefit Plans (Funded Status) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 31,381	$ 65,108	$ 61,256
Plan assets at fair value at end of year	0	25,225	21,175
SERPs
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	31,381	65,108	61,256
Accumulated benefit obligation	31,381	65,108	61,256
Plan assets at fair value at end of year	$ 0	$ 25,225	$ 21,175