Litigation Litigation (Details Textual) $ in Millions	6 Months Ended
Jun. 30, 2015 USD ($) Homebuilder Defendants	Dec. 31, 2014 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Litigation settlement charge	$ 48
Number of defendants named in class action lawsuits \| Defendants	7
Homebuilders asserting individual claims \| Homebuilder	12
Litigation settlement accrual	$ 48	$ 48
Accrual for probable and reasonably estimable liability for environmental cleanup	$ 16	$ 16

Carrying amount of reserve for known or estimated probable loss from litigation, which may include attorneys' fees and other litigation costs, which is expected to be paid within one year of the date of the statement of financial position.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.25)

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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 55

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=6396582&loc=d3e15243-108350

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant