Debt (Narrative) (Details) (Subsequent Event [Member], USD $) In Millions, unless otherwise specified	0 Months Ended
Jul. 30, 2014	Jul. 30, 2014
Senior Notes [Member] \| Secured Debt [Member] \| Lone Star [Member]
Debt Instrument [Line Items]
Face amount	$ 360	$ 360
senior secured limited-recourse term loan due 2019 [Member] \| An indirect wholly-owned subsidiary of NEECH [Member]
Debt Instrument [Line Items]
Face amount		$ 400
Interest Rate Terms	variable
Minimum [Member] \| Senior Notes [Member] \| Secured Debt [Member] \| Lone Star [Member]
Debt Instrument [Line Items]
Stated interest rate	2.45%	2.45%
Maximum [Member] \| Senior Notes [Member] \| Secured Debt [Member] \| Lone Star [Member]
Debt Instrument [Line Items]
Stated interest rate	4.42%	4.42%

Face (par) amount of debt instrument at time of issuance.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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- Definition

Description of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets.

+ References

+ Details

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- Details

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Balance Type:	na
Period Type:	duration