Long-term Debt - Textual (Details) - USD ($)		1 Months Ended		3 Months Ended	12 Months Ended			45 Months Ended
	Jan. 29, 2021	Sep. 30, 2020	Apr. 30, 2018	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020	Nov. 30, 2020	Aug. 09, 2018	Apr. 11, 2018	Dec. 31, 2017	Sep. 18, 2017	Apr. 03, 2017	Feb. 15, 2017
Debt Instrument [Line Items]
Debt issuance cost				$ 42,700,000	$ 42,700,000	$ 55,500,000		$ 42,700,000
Interest expense					139,800,000	144,200,000	$ 151,300,000
Line of credit facility, remaining borrowing capacity				200,000	200,000			200,000
Amount borrowed from accounts receivable securitization		$ 60,000,000.0
Subsequent Event
Debt Instrument [Line Items]
Payment for debt exchange	$ 9,400,000
Accounts Receivable Securitization Program, April 3, 2020
Debt Instrument [Line Items]
Line of credit facility, remaining borrowing capacity				19,300,000	19,300,000			19,300,000
Exit facility, maximum borrowing capacity														$ 250,000,000.0
Senior Notes | 6.000% Senior Secured Notes due March 2022
Debt Instrument [Line Items]
Debt principal amount															$ 500,000,000.0
Long-term debt				$ 459,000,000.0	$ 459,000,000.0	459,000,000.0		$ 459,000,000.0
Stated interest rate				6.00%	6.00%			6.00%
Debt instrument repurchase amount						41,000,000.0
Debt instrument repurchase amount, excluding interest						39,900,000
Senior Notes | 6.000% Senior Secured Notes due March 2022 | Subsequent Event
Debt Instrument [Line Items]
Aggregate principal amount of debt exchanged	398,700,000
Long-term debt	60,300,000
Senior Notes | 6.375% Senior Secured Notes due March 2025
Debt Instrument [Line Items]
Debt principal amount															500,000,000.0
Long-term debt				$ 500,000,000.0	$ 500,000,000.0	500,000,000.0		$ 500,000,000.0
Stated interest rate				6.375%	6.375%			6.375%
Priority liens term, percentage of capital stock of each domestic restricted subsidiary				100.00%	100.00%			100.00%
Priority liens term, percentage of capital stock of each first tier foreign subsidiary				100.00%	100.00%			100.00%
Senior Notes | 6.00% And 6.375% Senior Secured Notes, Successor Notes
Debt Instrument [Line Items]
Debt issuance cost															$ 49,500,000
Interest expense					$ 72,200,000	72,000,000.0	71,900,000
Senior Notes | Successor Credit Agreement
Debt Instrument [Line Items]
Debt instrument, restricted payments basket						150,000,000.0				$ 650,000,000.0
Senior Notes | 10.00% Senior Secured Notes Due 2024 (New Co-Issuer Notes) | Subsequent Event
Debt Instrument [Line Items]
Debt principal amount	$ 193,900,000
Stated interest rate	10.00%
Debt covenant, liquidity attributable to co-issuers limit (minimum)	$ 60,000,000.0
Debt secured liens term, percentage of capital stock	100.00%
Senior Notes | 8.500% Senior Secured Notes due 2024 (New Peabody Notes) | Subsequent Event
Debt Instrument [Line Items]
Debt principal amount	$ 195,100,000
Stated interest rate	8.50%
Interest rate per annum in cash	6.00%
Interest rate per annum paid-in-kind	2.50%
Senior Notes | New Co-Issuer Term Loans | Subsequent Event
Debt Instrument [Line Items]
Debt amount incurred	$ 206,000,000.0
Stated interest rate	10.00%
Senior Notes | New Company LC Agreement [Member] | Subsequent Event
Debt Instrument [Line Items]
Debt covenant, unrestricted subsidiaries' liquidity	$ 200,000,000.0
Refinancing transactions, principal repurchase basis	4
Refinancing transactions, principal amount basis for purchase	$ 1
Refinancing transactions, debt repurchases period	30 days
Term Loan | Successor Credit Agreement
Debt Instrument [Line Items]
Debt principal amount				$ 400,000,000.0	400,000,000.0			$ 400,000,000.0						$ 950,000,000.0
Interest expense					15,600,000	22,200,000	24,000,000.0
Debt instrument, restricted payments basket										$ 19,800,000
Basis spread on variable rate			2.75%
Original issue discount and deferred finance costs				$ 37,300,000	37,300,000			$ 37,300,000
Debt instrument, periodic payment					$ 1,000,000.0
Debt instrument, voluntary principal prepayment				101.00%	101.00%			101.00%
Mandatory principal prepayment, percent of excess cash flow				75.00%	75.00%			75.00%
Mandatory principal prepayment, if required, period payable, threshold					100 days
Excess proceeds from sales of assets, threshold ($10 million or greater)				$ 10,000,000.0	$ 10,000,000.0			$ 10,000,000.0
Repayments of debt			$ 46,000,000.0					561,000,000.0
Payment for debt extinguishment or debt prepayment cost							546,000,000.0	546,000,000.0
Floor interest rate											1.00%
Debt instrument, extended term			3 years
Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt				216,000,000.0	216,000,000.0	0		216,000,000.0
Revolving Credit Facility | 2017 Revolver
Debt Instrument [Line Items]
Debt issuance cost				5,700,000	5,700,000			5,700,000				$ 4,700,000
Interest expense					15,900,000	$ 6,200,000	$ 7,200,000
2019 Revolver commitments, matures 2023				540,000,000.0	540,000,000.0			540,000,000.0
2019 Revolver commitments, matures 2020									$ 25,000,000.0
Unrestricted cash, net limit				800,000,000.0	800,000,000.0			800,000,000.0
Proceeds from lines of credit					315,000,000.0
Repayments of lines of credit					99,000,000.0
Aggregate letters of credit, maximum				$ 323,800,000	$ 323,800,000			$ 323,800,000
Revolving credit facility, fee on unused borrowings					0.50%
Financing facility, base interest rate				3.375%	3.375%			3.375%
Exit facility, maximum borrowing capacity				$ 565,000,000.0	$ 565,000,000.0			$ 565,000,000.0				$ 350,000,000.0
London Interbank Offered Rate (LIBOR) | Accounts Receivable Securitization Program, April 3, 2020
Debt Instrument [Line Items]
Basis spread on variable rate				1.50%
London Interbank Offered Rate (LIBOR) | Term Loan | Successor Credit Agreement
Debt Instrument [Line Items]
Basis spread on variable rate					2.75%
London Interbank Offered Rate (LIBOR) | Revolving Credit Facility | 2017 Revolver
Debt Instrument [Line Items]
Basis spread on variable rate					3.25%
Total Leverage Ratio Less or Equal to 2.00 to 1.00 Greater Than 1.50 to 1.00 | Term Loan | Successor Credit Agreement
Debt Instrument [Line Items]
Mandatory principal prepayment, percent of excess cash flow				50.00%	50.00%			50.00%
Total Leverage Ratio Less or Equal to 2.00 to 1.00 Greater Than 1.50 to 1.00 | Maximum | Term Loan | Successor Credit Agreement
Debt Instrument [Line Items]
Total Leverage Ratio				2.00	2.00			2.00
Total Leverage Ratio Less or Equal to 2.00 to 1.00 Greater Than 1.50 to 1.00 | Minimum | Term Loan | Successor Credit Agreement
Debt Instrument [Line Items]
Total Leverage Ratio				1.50	1.50			1.50
Total Leverage Ratio Less or Equal to 1.50 to 1.00 Greater Than 1.00 to 1.00 | Term Loan | Successor Credit Agreement
Debt Instrument [Line Items]
Mandatory principal prepayment, percent of excess cash flow				25.00%	25.00%			25.00%
Total Leverage Ratio Less or Equal to 1.50 to 1.00 Greater Than 1.00 to 1.00 | Maximum | Term Loan | Successor Credit Agreement
Debt Instrument [Line Items]
Total Leverage Ratio				1.50	1.50			1.50
Total Leverage Ratio Less or Equal to 1.50 to 1.00 Greater Than 1.00 to 1.00 | Minimum | Term Loan | Successor Credit Agreement
Debt Instrument [Line Items]
Total Leverage Ratio				1.00	1.00			1.00
Total Leverage Ratio Less or Equal to 1.00 to 1.00 | Term Loan | Successor Credit Agreement
Debt Instrument [Line Items]
Mandatory principal prepayment, percent of excess cash flow				0.00%	0.00%			0.00%
Total Leverage Ratio				1.00	1.00			1.00
Total Leverage Ration Less Or Equal 2.00 to 1.00 | Revolving Credit Facility | 2017 Revolver
Debt Instrument [Line Items]
Total Leverage Ratio				2.00	2.00			2.00
Revolving Credit Facility | Line of Credit | Subsequent Event
Debt Instrument [Line Items]
Repayments of lines of credit	$ 10,000,000.0
Revolving Credit Facility | Line of Credit | 2017 Revolver
Debt Instrument [Line Items]
Long-term debt													$ 350,000,000.0