Supplemental Schedule Of Cash Flow Information (Schedule Of Supplemental Cash Flow Information) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Supplemental Schedule Of Cash Flow Information [Abstract]
Capital leases issued for equipment	$ 8,308us-gaap_CapitalLeaseObligationsIncurred	$ 3,928us-gaap_CapitalLeaseObligationsIncurred
Asset retirement obligation additions	$ 13	$ 23

The increase during the period in capital lease obligations due to entering into new capital leases.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4313-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

Name:	us-gaap_CapitalLeaseObligationsIncurred
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration