Pensions and Other Postretirement Plans (Reconciliation of Change in Pension Plan Assets Fair Value Using Level 3 Inputs) (Details 10) - Level 3 [Member] - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Private investment fund [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of assets at beginning of year	$ 0	$ 0
Purchases, sales and settlements, net	150,000	0
Gains relating to assets sold	0	0
(Losses) gains relating to assets still held at year-end	1,854	0
Fair value of assets at end of year	151,854	0
U.S. stock index fund [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of assets at beginning of year	601,395	706,202
Purchases, sales and settlements, net	(425,000)	(80,000)
Gains relating to assets sold	68,658	2,819
(Losses) gains relating to assets still held at year-end	77,176	(27,626)
Fair value of assets at end of year	$ 322,229	$ 601,395

Amount, measured using unobservable inputs, of increase (decrease) in plan assets of defined benefit plan from actual return (loss) on assets sold.

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- Definition

Amount, measured using unobservable inputs, of increase (decrease) in plan assets of defined benefit plan from actual return (loss) on assets still held.

+ References

+ Details

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

Amount, measured using unobservable input, of increase (decrease) in plan asset of defined benefit plan from purchase, sale and settlement of trade associated with underlying investment.

+ References

+ Details

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