The number of shares converted in a noncash (or part noncash) transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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Postretirement Health Care and Life Insurance Benefits Net Periodic Postretirement Benefit Cost(Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Apr. 01, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Predecessor
Components of net periodic postretirement benefit cost
Actuarial gain			$ (32.3)
Predecessor \| Postretirement Health Care and Life Insurance Benefits [Member]
Components of net periodic postretirement benefit cost
Service cost for benefits earned	$ 2.3		10.4	$ 11.2
Interest cost on accumulated postretirement benefit obligation	8.4		34.5	33.8
Amortization of prior service (credit) cost	(2.3)		(9.2)	(6.8)
Amortization of actuarial loss	5.5		20.4	24.9
Actuarial gain	0.0		0.0	0.0
Net periodic pension cost	$ 13.9		$ 56.1	$ 63.1
Successor
Components of net periodic postretirement benefit cost
Service cost for benefits earned		$ 6.9
Interest cost on accumulated postretirement benefit obligation		$ 24.2
Conversion of Stock, Shares Converted		(17.2)
Actuarial gain		$ 22.0
Successor \| Postretirement Health Care and Life Insurance Benefits [Member]
Components of net periodic postretirement benefit cost
Service cost for benefits earned		6.9
Interest cost on accumulated postretirement benefit obligation		24.2
Amortization of prior service (credit) cost		0.0
Amortization of actuarial loss		0.0
Actuarial gain		22.0
Net periodic pension cost		$ 9.1