XML 72 R59.htm IDEA: XBRL DOCUMENT
v3.7.0.1

Stockholders' Equity (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2016
Stockholders' Equity (Tables) [Abstract] |
Summary of common stock activity | The following table summarizes common stock activity from January 1, 2014 to December 31, 2016:
| 2016 |  | 2015 |  | 2014
| (In millions)
Shares outstanding at the beginning of the year | 18.5 |  |  | 18.1 |  |  | 18.0 |
Stock grants to employees | — |  |  | 0.2 |  |  | 0.1 |
Performance share contribution 401k | — |  |  | 0.2 |  |  | — |
Shares outstanding at the end of the year | 18.5 |  |  | 18.5 |  |  | 18.1 |

X
- Definition Stockholders' Equity (Tables) [Abstract] + References No definition available. + Details
Name: | btu_StockholdersEquityTablesAbstract
Namespace Prefix: | btu_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Summary of common stock activity. + References No definition available. + Details
Name: | btu_SummaryOfCommonStockActivityTextBlock
Namespace Prefix: | btu_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration