Accounting Developments (Details) (USD $) In Millions	6 Months Ended
Jun. 30, 2011
Minimum [Member]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ 400.0
Maximum [Member]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ 600.0

Represents the quantification of the effect of adopting the new accounting standard or change in accounting principle expected by the entity to have a significant effect on the entity's financial statements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 25
-Section 65
-Paragraph 1
-Subparagraph (c)(4)
-URI http://asc.fasb.org/extlink&oid=6940631&loc=SL6749767-165964

Name:	us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration