Subsequent Events (Details) (USD $) In Millions, unless otherwise specified	2 Months Ended
Nov. 30, 2013 Subsequent Event [Member]	Aug. 06, 2013 Permian Basin [Member] acre	Nov. 30, 2013 Haynesville Shale [Member] Subsequent Event [Member] acre
Subsequent Event [Line Items]
Number of acres acquired, gross		9,100	900
Number of acres acquired, net		4,800	900
Payments to Acquire Land	$ 9.7

The cash outflow from the acquisition of real estate intended to generate income for the owner; excludes land acquired for use by the owner.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 17

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3213-108585

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