1.0.0.3 false Subsequent Events false 1 $ false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 USDEPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 2 Subsequent Events [Abstract] 0 anr_SubsequentEventsAbstract anr false na duration string Subsequent Events. false false false false false true false false false 1 false false 0 0 false false Subsequent Events. false 3 Subsequent Events 1 us-gaap_ScheduleOfSubsequentEventsTextBlock us-gaap true na duration string No definition available. false false false false false false false false false 1 false false 0 0 <!--DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" --> <!-- Begin Block Tagged Note 27 - us-gaap:ScheduleOfSubsequentEventsTextBlock--> <div style="font-family: 'Times New Roman',Times,serif; margin-left: .25in; width: 7.20in"> <div align="left" style="font-size: 10pt; margin-top: 10pt"><b>(27)&#160;Subsequent Events</b> </div> <div align="left" style="font-size: 10pt; margin-top: 10pt; text-indent: 4%">In February&#160;2010, the Company entered into a 50/50 joint venture with Rice Drilling Company, LLC (the &#8220;Joint Venture&#8221;) to develop a portion of the Company&#8217;s approximately 20,000 acres of Marcellus shale gas reserves in southwestern Pennsylvania. Subsequent to the agreement, the initial phase of development began and the Joint Venture is currently drilling the first of four wells planned for 2010. </div> </div> <!--DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" --> <!-- Begin Block Tagged Note false false No definition available. No authoritative reference available. false false 1 2 false UnKnown UnKnown UnKnown false true