Pension Plans (Pension Plan Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Qualified Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned during the year	$ 5,100	$ 4,897	$ 4,794
Interest cost on projected benefit obligation	(26,422)	(23,804)	(24,358)
Expected return on plan assets	(42,560)	(47,841)	(42,049)
Recognized net loss	15,260	11,370	13,943
Additional amount recognized due to curtailment/settlement	0	0	0
Net pension benefit cost (income)	4,222	(7,770)	1,046
Change in net gain or (loss)	3,295	27,203	(6,607)
Amortization of net loss	(15,260)	(11,370)	(13,943)
Total recognized in other comprehensive (loss) income	(11,965)	15,833	(20,550)
Total recognized in net periodic benefit cost and other comprehensive (loss) income	(7,743)	8,063	(19,504)
SERP
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned during the year	0	0	0
Interest cost on projected benefit obligation	(237)	(246)	(241)
Expected return on plan assets	0	0	0
Recognized net loss	245	248	146
Additional amount recognized due to curtailment/settlement	0	46	305
Net pension benefit cost (income)	482	540	692
Change in net gain or (loss)	720	(325)	347
Amortization of net loss	(245)	(248)	(146)
Total recognized in other comprehensive (loss) income	475	(573)	201
Total recognized in net periodic benefit cost and other comprehensive (loss) income	$ 957	$ (33)	$ 893