Retirement and Compensation Plans Funding Status and Net Periodic Pension Costs (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets beginning of period	$ 262,276,000
Fair Value of Plan Assets, End of period	291,071,000	$ 262,276,000
United States Pension Plan of US Entity [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Projected Benefit Obligation	319,420,000	339,139,000
Defined Benefit Plan, Service Cost	5,795,000	5,892,000	$ 5,295,000
Defined Benefit Plan, Interest Cost	14,447,000	13,472,000	13,919,000
Defined Benefit Plan, Actuarial Gain (Loss)	(15,767,000)	13,281,000
Defined Benefit Plan, Benefits Paid	(18,975,000)	(2,501,000)
Defined Benefit Plan, Settlements, Benefit Obligation	0	(23,301,000)
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Projected Benefit Obligation	336,454,000	319,420,000	339,139,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets beginning of period	262,276,000	257,010,000
Defined Benefit Plan, Actual Return on Plan Assets	17,770,000	1,068,000
Defined Benefit Plan, Contributions by Employer	30,000,000	30,000,000
Defined Benefit Plan, Benefits Paid	(18,975,000)	(2,501,000)
Defined Benefit Plan, Settlements, Plan Assets	0	(23,301,000)
Fair Value of Plan Assets, End of period	291,071,000	262,276,000	257,010,000
Defined Benefit Plan, Funded Status of Plan	(45,383,000)	(57,144,000)
Defined Benefit Plan, Accumulated Benefit Obligation	297,753,000	279,858,000
Other Pension Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Projected Benefit Obligation	22,275,000	26,729,000
Defined Benefit Plan, Service Cost	335,000	435,000	269,000
Defined Benefit Plan, Interest Cost	966,000	1,000,000	1,077,000
Defined Benefit Plan, Actuarial Gain (Loss)	(3,317,000)	2,812,000
Defined Benefit Plan, Benefits Paid	(2,308,000)	(3,077,000)
Defined Benefit Plan, Settlements, Benefit Obligation	0	0
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Projected Benefit Obligation	24,585,000	22,275,000	26,729,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets beginning of period	0	0
Defined Benefit Plan, Actual Return on Plan Assets	0	0
Defined Benefit Plan, Contributions by Employer	2,308,000	3,077,000
Defined Benefit Plan, Benefits Paid	(2,308,000)	(3,077,000)
Defined Benefit Plan, Settlements, Plan Assets	0	0
Fair Value of Plan Assets, End of period	0	0	$ 0
Defined Benefit Plan, Funded Status of Plan	(24,585,000)	(22,275,000)
Defined Benefit Plan, Accumulated Benefit Obligation	$ 21,407,000	$ 20,980,000