Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Feb. 16, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	1-16463
Entity Registrant Name	PEABODY ENERGY CORP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	13-4004153
Entity Address, Address Line One	701 Market Street,
Entity Address, City or Town	St. Louis,
Entity Address, State or Province	MO
Entity Address, Postal Zip Code	63101-1826
City Area Code	314
Local Phone Number	342-3400
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	BTU
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 196.3
Entity Bankruptcy Proceedings, Reporting Current	true
Entity Common Stock, Shares Outstanding		98,244,140
Documents Incorporated by Reference	Portions of the Company’s Proxy Statement to be filed with the Securities and Exchange Commission in connection with the Company’s 2021 Annual Meeting of Shareholders (the Company’s 2021 Proxy Statement) are incorporated by reference into Part III hereof. Other documents incorporated by reference in this report are listed in the Exhibit Index of this Form 10-K.
Entity Central Index Key	0001064728
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false