Pension and Postretirement Plans (Obligation, Asset, and Funding Information) (Details 1) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plans [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at begining of year	$ 1,254,298,000	$ 1,317,480,000
Service cost	20,461,000	26,294,000	$ 27,792,000
Interest cost	51,608,000	52,613,000	51,825,000
Amendments	0	4,606,000
Actuarial (gain) loss	(32,203,000)	(57,834,000)
Benefits paid	(60,076,000)	(85,542,000)
Curtailment	0	(3,319,000)
Settlement	(73,191,000)	0
Benefit obligation at end of year	1,160,897,000	1,254,298,000	1,317,480,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of assets at beginning of year	2,234,268,000	2,469,968,000
Actual return on plan assets	(58,511,000)	(150,158,000)
Employer contributions	0	0	0
Benefits paid	(60,076,000)	(85,542,000)
Settlement	(73,191,000)	0
Fair value of assets at end of year	2,042,490,000	2,234,268,000	2,469,968,000
Funded status	881,593,000	979,970,000
Supplemental Executive Retirement Plan (SERP) [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at begining of year	105,004,000	116,083,000
Service cost	985,000	1,946,000	1,493,000
Interest cost	4,384,000	4,550,000	4,397,000
Actuarial (gain) loss	1,120,000	(6,544,000)
Benefits paid	(4,967,000)	(6,083,000)
Curtailment	0	(4,948,000)
Benefit obligation at end of year	106,526,000	105,004,000	116,083,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of assets at beginning of year	0	0
Employer contributions	4,967,000	6,083,000
Benefits paid	(4,967,000)	(6,083,000)
Fair value of assets at end of year	0	0	0
Funded status	(106,526,000)	(105,004,000)
Other Postretirement Plans [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at begining of year	37,391,000	41,957,000
Service cost	1,386,000	1,331,000	1,500,000
Interest cost	1,230,000	1,299,000	1,448,000
Actuarial (gain) loss	(14,984,000)	(5,296,000)
Benefits paid, net of Medicare subsidy	(852,000)	(1,900,000)
Benefit obligation at end of year	24,171,000	37,391,000	41,957,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of assets at beginning of year	0	0
Employer contributions	852,000	1,900,000
Benefits paid, net of Medicare subsidy	(852,000)	(1,900,000)
Fair value of assets at end of year	0	0	$ 0
Funded status	$ (24,171,000)	$ (37,391,000)