v2.4.0.6

Summary of Significant Accounting Principles and Practices (Details) (USD $) | 12 Months Ended
--- | ---
Dec. 31, 2011 Y | Dec. 31, 2010 | Dec. 31, 2009
Cash and Cash Equivalents |  |  |
Cash and cash equivalents, restricted | $ 191,000,000 | $ 60,000,000 |
Operating funds in U.K. | 120,000,000 |  |
Fiduciary Assets and Liabilities |  |  |
Premium trust balances | 4,200,000,000 | 3,500,000,000 |
Allowance for Doubtful Accounts |  |  |
Allowance for doubtful accounts receivable | 104,000,000 | 102,000,000 |
Goodwill and Intangible Assets |  |  |
Minimum useful life of finite-lived intangible assets (in years) | 1 |  |
Maximum useful life of finite-lived intangible assets (in years) | 13 |  |
Weighted-average original life of finite-lived intangible assets (in years) | 10 |  |
Foreign Currency |  |  |
Effect of foreign exchange gains (losses) on the consolidated statements of income | 10,000,000 | (18,000,000) | (26,000,000)
Derivative losses | $ 20,000,000 | $ 11,000,000 | $ 15,000,000
Buildings |  |  |
Fixed Assets |  |  |
Fixed assets, original life, weighted-average (in years) | 35 |  |
Automobiles |  |  |
Fixed Assets |  |  |
Fixed assets, original life, weighted-average (in years) | 6 |  |
Minimum |  |  |
Revenue Recognition |  |  |
Term of outsourcing contracts for benefit services (in years) | 3 |  |
Term of outsourcing contracts for HR BPO services (in years) | 5 |  |
Short-term Investments |  |  |
Short-term investment, maturity period (in months/year) | 3 |  |
Consolidation of Variable Interest Entities |  |  |
Ownership percentage, criteria for consolidation | 50.00% |  |
Minimum | Software |  |  |
Fixed Assets |  |  |
Fixed assets, useful life, minimum (in years) | 3 |  |
Minimum | Furniture, fixtures and equipment |  |  |
Fixed Assets |  |  |
Fixed assets, useful life, minimum (in years) | 4 |  |
Minimum | Computer equipment |  |  |
Fixed Assets |  |  |
Fixed assets, useful life, minimum (in years) | 4 |  |
Maximum |  |  |
Revenue Recognition |  |  |
Term of outsourcing contracts for benefit services (in years) | 5 |  |
Term of outsourcing contracts for HR BPO services (in years) | 10 |  |
Cash and Cash Equivalents |  |  |
Cash and cash equivalents, maturity period (in months) | 3 |  |
Short-term Investments |  |  |
Short-term investment, maturity period (in months/year) | 1 |  |
Maximum | Software |  |  |
Fixed Assets |  |  |
Fixed assets, useful life, maximum (in years) | 7 |  |
Maximum | Furniture, fixtures and equipment |  |  |
Fixed Assets |  |  |
Fixed assets, useful life, maximum (in years) | 10 |  |
Maximum | Computer equipment |  |  |
Fixed Assets |  |  |
Fixed assets, useful life, maximum (in years) | 6 |  |

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