Supplemental Guarantor/Non-Guarantor Financial Information (Details Textuals)	12 Months Ended
Dec. 31, 2016
Supplemental Guarantor Non Guarantor Financial Information [Abstract]
Percent of ownership of certain U.S. subsidiaries that fully and unconditionally guarantee the Senior Notes	100.00%

Percent of ownership of certain U.S. subsidiaries that fully and unconditionally guarantee the Senior Notes

No definition available.

Name:	btu_PercentofownershipofcertainU.S.subsidiariesthatfullyandunconditionallyguaranteetheSeniorNotes
Namespace Prefix:	btu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration