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Voluntary Reorganization under Chapter 11 Proceedings - Narrative (Details) - USD ($) shares in Millions				1 Months Ended		3 Months Ended	9 Months Ended	12 Months Ended
	Feb. 10, 2017	Oct. 04, 2016	Oct. 01, 2016	Feb. 28, 2017	Feb. 09, 2017	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2018	Oct. 31, 2018
Series A Warrants
Restructuring Cost and Reserve [Line Items]
Issuance of common stock (in shares)								4.6
Series B Warrants
Restructuring Cost and Reserve [Line Items]
Issuance of common stock (in shares)								2.0
Predecessor \| 7.0% Convertible perpetual preferred stock
Restructuring Cost and Reserve [Line Items]
Dividend rate, percentage							7.00%
Predecessor \| 8.5% Convertible perpetual preferred stock
Restructuring Cost and Reserve [Line Items]
Dividend rate, percentage							8.50%
Revolving Credit Facility \| Amended New Credit Facility
Restructuring Cost and Reserve [Line Items]
Line of credit facility, current borrowing capacity	$ 425,000,000.0								$ 350,000,000.0
Convertible Debt \| New Convertible Notes
Restructuring Cost and Reserve [Line Items]
Face amount of debt instrument			$ 281,800,000				$ 281,800,000
Common stock issued for debt (in shares)	14.1		15.0		0.3	0.7
Fair value of debt			$ 445,700,000				445,700,000
Convertible Debt \| Successor \| New Convertible Notes
Restructuring Cost and Reserve [Line Items]
Common stock issued for debt (in shares)				14.1
Secured Notes \| Building Note
Restructuring Cost and Reserve [Line Items]
Face amount of debt instrument			35,000,000.0				35,000,000.0
Fair value of debt			36,600,000				$ 36,600,000
Proceeds from issuance of debt			$ 26,800,000
Plan of Reorganization \| Predecessor \| 7.0% Convertible perpetual preferred stock
Restructuring Cost and Reserve [Line Items]
Dividend rate, percentage		7.00%
Plan of Reorganization \| Predecessor \| 8.5% Convertible perpetual preferred stock
Restructuring Cost and Reserve [Line Items]
Dividend rate, percentage		8.50%
Plan of Reorganization \| Successor \| New Common Stock
Restructuring Cost and Reserve [Line Items]
Common stock, shares authorized (in shares)		18.9
Plan of Reorganization \| Successor \| New First Lien Exit Facility
Restructuring Cost and Reserve [Line Items]
Cash collateral		$ 50,000,000.0
Plan of Reorganization \| Successor \| Holders of Senior Secured Notes \| New Common Stock
Restructuring Cost and Reserve [Line Items]
Issuance of common stock (in shares)		13.7
Plan of Reorganization \| Successor \| Holders of Unsecured Claims
Restructuring Cost and Reserve [Line Items]
Cash payments for prepetition obligations		$ 36,700,000
Plan of Reorganization \| Successor \| Holders of Unsecured Claims \| Series A Warrants
Restructuring Cost and Reserve [Line Items]
Issuance of common stock (in shares)		4.5
Number of shares to be issued (in shares)		4.9
Plan of Reorganization \| Successor \| Holders of Unsecured Claims \| Series B Warrants
Restructuring Cost and Reserve [Line Items]
Issuance of common stock (in shares)		1.9
Number of shares to be issued (in shares)		2.1
Plan of Reorganization \| Successor \| Holders of Unsecured Claims \| New Common Stock
Restructuring Cost and Reserve [Line Items]
Issuance of common stock (in shares)		5.2
Number of shares to be issued (in shares)		5.7
Plan of Reorganization \| Revolving Credit Facility \| Successor \| New First Lien Exit Facility
Restructuring Cost and Reserve [Line Items]
Line of credit facility, current borrowing capacity		$ 425,000,000.0
Plan of Reorganization \| Revolving Credit Facility \| Successor \| Holders of Senior Credit Facility
Restructuring Cost and Reserve [Line Items]
Cash payments for prepetition obligations		35,000,000.0
Plan of Reorganization \| Convertible Debt \| Successor \| Holders of Senior Secured Notes
Restructuring Cost and Reserve [Line Items]
Face amount of debt instrument		281,800,000
Plan of Reorganization \| Secured Notes \| Successor \| Building Note
Restructuring Cost and Reserve [Line Items]
Face amount of debt instrument		35,000,000.0
Fair value of debt		36,600,000
Proceeds from issuance of debt		$ 26,800,000