Acquisition (Tables) | 9 Months Ended | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Sep. 30, 2011 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Acquisition [Abstract] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Preliminary Purchase Price Allocated to Assets Acquired and Liabilities Assumed | The preliminary purchase price was allocated to the assets acquired and liabilities assumed based on the estimated fair values as follows (in millions):
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