Subsequent Events (Details) (USD $) In Billions, unless otherwise specified	Mar. 31, 2013
Subsequent Event [Line Items]
Business Acquisition, Cost of Acquired Entity, Purchase Price	$ 2.4
Business Acquisition, Purchase Price Allocation, Liabilities Assumed	1.3
Business Acquisition, Equity Contributed From Parent	1.3
Business Acquisition, Loan From Parent	0.8
Business Acquisition, Amount Expected to Pay	$ 1.8

The amount of acquisition cost of a business combination allocated to liabilities assumed.

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

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 98-1

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 37

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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