Pension Plan and Employee Benefits, Unobservable Input Reconciliation (Details) - Pension Benefits [Member] - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
Apr. 12, 2016	Dec. 31, 2016	Dec. 31, 2015
Predecessor [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation[Roll Forward]
Fair value of plan assets at beginning of year	$ 383,532		$ 412,803
Fair value of plan assets at end of year	398,515		383,532
Predecessor [Member] \| Real estate funds [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation[Roll Forward]
Fair value of plan assets at beginning of year	17,890		18,792
Realized gains	71		9
Unrealized gains (losses)	89		(148)
Purchases	26		679
Sales	(205)		(1,442)
Fair value of plan assets at end of year	17,871		$ 17,890
Successor [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation[Roll Forward]
Fair value of plan assets at end of year	$ 398,515	$ 403,715
Successor [Member] \| Real estate funds [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation[Roll Forward]
Fair value of plan assets at beginning of year		17,871
Realized gains		151
Unrealized gains (losses)		226
Purchases		570
Sales		(151)
Fair value of plan assets at end of year		$ 18,668

Amount of decrease in plan assets from sales.

No definition available.

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- Definition

Actual return on plan assets, separately identifying the amount related to assets sold during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(02)(A)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (c)(iv)(02)(A)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e2446-114920

+ Details

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- Definition

Actual return on plan assets, separately identifying the amount related to assets still held at the reporting date.

+ 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.

+ Details

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- Definition

Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 30
-Section 35
-Paragraph 50
-URI http://asc.fasb.org/extlink&oid=64937038&loc=d3e12355-114930

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Plan Assets
-URI http://asc.fasb.org/extlink&oid=6749337

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Plan Assets
-URI http://asc.fasb.org/extlink&oid=6520858

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- Definition

Amount of increase (decrease) in plan assets from purchases, sales and settlement of plan obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(02)(B)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (c)(iv)(02)(B)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e2446-114920

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