Retirement Plans (Changes in the Projected Benefit Obligation and Plan Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Plan
Projected benefit obligation:
Benefit obligation at beginning of year	$ 121,361	$ 123,968
Service cost	0	639	$ 1,041
Interest cost	4,356	4,966	5,335
Net actuarial loss (gain)	(7,048)	10,131
Benefits paid	(7,237)	(6,432)
Curtailment	0	(11,911)
Benefit obligation at end of year	111,432	121,361	123,968
Fair value of plan assets:
Fair value of plan assets at beginning of year	145,901	132,751
Actual return on plan assets	(10,312)	19,582
Employer contributions	0	0
Benefits paid	(7,237)	(6,432)
Fair value of plan assets at end of year	128,352	145,901	132,751
Funded (unfunded) status at December 31	16,920	24,540
Accumulated benefit obligation	111,432	121,361
Postretirement Plan
Projected benefit obligation:
Benefit obligation at beginning of year	2,512	2,601
Service cost	3	5	9
Interest cost	82	94	132
Net actuarial loss (gain)	(208)	10
Benefits paid	(189)	(198)
Curtailment	0	0
Benefit obligation at end of year	2,200	2,512	2,601
Fair value of plan assets:
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	0	198
Benefits paid	0	(198)
Fair value of plan assets at end of year	0	0	0
Funded (unfunded) status at December 31	(2,200)	(2,512)
Accumulated benefit obligation	2,200	2,512
SERP
Projected benefit obligation:
Benefit obligation at beginning of year	2,423	2,567
Service cost	0	61	77
Interest cost	12	69	92
Net actuarial loss (gain)	(36)	(274)
Benefits paid	(2,062)	0
Curtailment	0	0
Benefit obligation at end of year	337	2,423	2,567
Fair value of plan assets:
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	0	0
Benefits paid	0	0
Fair value of plan assets at end of year	0	0	$ 0
Funded (unfunded) status at December 31	(337)	(2,423)
Accumulated benefit obligation	$ 337	$ 2,423