Sale of Assets (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended
	Sep. 30, 2014 acre	Mar. 31, 2014	Feb. 28, 2014	Dec. 31, 2013	Apr. 30, 2013 acre
Sale Of Assets [Line Items]
Sale of interest, acres	7,500
Proceeds from sale of interest in wells and related leasehold interest	$ 29.3	$ 71.0		$ 34.5	$ 6.8
Escrow deposits related to property sales		6.8
Amount In escrow received	4.3
Remaining amount in escrow	2.5
Proceeds from sale of property in Ward County, Texas			5.1
Percentage of assets contributed in limited partnership					5.00%
Percentage of assets of limited partnership purchased from Clayton Williams Energy Inc.					95.00%
Value of assets of limited partnership purchased from Clayton Williams Energy Inc.					215.2
Sale of interest in wells, percent					75.00%
Sale of interest in net undeveloped land, acres					12,000
General Partner
Sale Of Assets [Line Items]
Percent of interest in limited partnership					5.00%
GE Energy Financial Services | Limited Partner
Sale Of Assets [Line Items]
Payments to acquire interest in limited partnership					$ 215.2
Limited partner ownership interest					95.00%