Chapter 11 Filing, Going Concern and Other Related Matters Reorganization Items (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended	12 Months Ended
	Aug. 02, 2018	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reorganization Items [Line Items]
Payments of Debt Issuance Costs							$ (24.4)	$ (23.5)	$ (27.1)
Write-off of deferred long-term debt issuance costs							54.8
Write-off of original issue net discount on debt subject to compromise	$ 35.7						27.1
Debtor-in-possession financing costs							43.4
Professional fees and other bankruptcy related costs							139.2
Provision for estimated damages on rejected executory contracts							29.3
Gain on write-off of net lease liabilities for rejected leases							(17.7)
Gain on vendor settlements of liabilities subject to compromise							(15.5)
Reorganization items, net		$ 41.1	$ 29.2	$ 85.4	$ 104.9		260.6	0.0	$ 0.0
Reorganization items, net [Member]
Reorganization Items [Line Items]
Payments of Debt Issuance Costs						$ (16.9)
Term Loan Commitments | Superpriority Term Loan Facility
Reorganization Items [Line Items]
Debtor-in-Possession Financing, Borrowings Outstanding		$ 500.0	$ 500.0			$ 500.0	$ 500.0	$ 0.0