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Significant Accounting Policies (Tables) | 12 Months Ended
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Dec. 31, 2011
Significant Accounting Policies [Abstract] |
Components of Operating Expenses | Operating expenses for the three years ended December 31, 2011 were (in millions):
| 2011 |  | 2010 |  | 2009
Salary and service costs | $ | 10,250.6 |  |  | $ | 9,214.2 |  |  | $ | 8,450.6 |
Office and general expenses | 1,950.8 |  |  | 1,868.1 |  |  | 1,895.2 |
Operating expenses | $ | 12,201.4 |  |  | $ | 11,082.3 |  |  | $ | 10,345.8 |

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