| **Derivative Financial Instruments and Risk Management (Details) (USD $)In Millions, unless otherwise specified**       | Mar. 31, 2013 |
|-------------------------------------------------------------------------------------------------------------------------|---------------|
| **Derivative**                                                                                                          |          |
| Deferred net losses, interest rate risk, to be reclassified from equity to current earnings over the next twelve months | $ 4           |

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| - Details**Name:**us-gaap_DerivativeLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
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| - Definition
The estimated net amount of unrealized gains or losses on interest rate cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=7668309&loc=d3e80748-113994Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 45 -Subparagraph b(2) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.
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