Employee Benefit Plans (Pension And Other Postretirement Benefit Costs) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Successor [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 2,991
Expected return on plan assets	(4,497)
Amortization of other actuarial losses (gains)	0
Net benefit cost (credit)	(1,506)
Successor [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	170
Interest cost	1,058
Amortization of prior service credits	0
Amortization of other actuarial losses (gains)	0
Net benefit cost (credit)	$ 1,228
Predecessor [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost		$ 3,338
Expected return on plan assets		(4,538)
Amortization of other actuarial losses (gains)		757
Net benefit cost (credit)		(443)
Predecessor [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		160
Interest cost		1,134
Amortization of prior service credits		(2,673)
Amortization of other actuarial losses (gains)		(566)
Net benefit cost (credit)		$ (1,945)