Pensions and Other Postretirement Plans (Obligation, Asset, and Funding Information) (Details 1) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Service cost	$ 22,656,000	$ 20,422,000	$ 18,221,000
Pension Plans [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at begining of year	1,020,356,000	1,116,569,000
Service cost	22,656,000	20,422,000	18,221,000
Interest cost	32,587,000	46,821,000	46,787,000
Amendments	69,000	5,725,000
Actuarial (gain) loss	78,900,000	124,285,000
Benefits paid	(73,232,000)	(64,354,000)
Special termination benefits	13,781,000	6,432,000
Settlement	0	(235,544,000)
Benefit obligation at end of year	1,095,117,000	1,020,356,000	1,116,569,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of assets at beginning of year	2,312,706,000	2,120,127,000
Actual return on plan assets	563,948,000	492,477,000
Employer contributions	0	0
Benefits paid	(73,232,000)	(64,354,000)
Settlement	0	(235,544,000)
Fair value of assets at end of year	2,803,422,000	2,312,706,000	2,120,127,000
Funded status	1,708,305,000	1,292,350,000
Supplemental Executive Retirement Plan (SERP) [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at begining of year	116,193,000	102,548,000
Service cost	954,000	858,000	819,000
Interest cost	3,678,000	4,314,000	3,865,000
Actuarial (gain) loss	7,448,000	15,544,000
Benefits paid	(5,974,000)	(7,071,000)
Benefit obligation at end of year	122,299,000	116,193,000	102,548,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of assets at beginning of year	0	0
Employer contributions	5,974,000	7,071,000
Benefits paid	(5,974,000)	(7,071,000)
Fair value of assets at end of year	0	0	0
Funded status	(122,299,000)	(116,193,000)
Other Postretirement Plans [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at begining of year	6,816,000	8,523,000
Service cost	0	0	892,000
Interest cost	167,000	289,000	620,000
Actuarial (gain) loss	(991,000)	(1,246,000)
Benefits paid, net of Medicare subsidy	(405,000)	(750,000)
Benefit obligation at end of year	5,587,000	6,816,000	8,523,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of assets at beginning of year	0	0
Employer contributions	405,000	750,000
Benefits paid, net of Medicare subsidy	(405,000)	(750,000)
Fair value of assets at end of year	0	0	$ 0
Funded status	$ (5,587,000)	$ (6,816,000)