Summary of Significant Accounting Principles and Practices (Details)	12 Months Ended				12 Months Ended
	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2013 GBP (£)	Dec. 31, 2013 Buildings [Member]	Dec. 31, 2013 Automobiles [Member]	Dec. 31, 2013 Minimum [Member]	Dec. 31, 2013 Minimum [Member] Software [Member]	Dec. 31, 2013 Minimum [Member] Furniture, fixtures and equipment [Member]	Dec. 31, 2013 Minimum [Member] Computer equipment [Member]	Dec. 31, 2013 Maximum [Member]	Dec. 31, 2013 Maximum [Member] Software [Member]	Dec. 31, 2013 Maximum [Member] Leasehold improvements [Member]	Dec. 31, 2013 Maximum [Member] Furniture, fixtures and equipment [Member]	Dec. 31, 2013 Maximum [Member] Computer equipment [Member]	Dec. 31, 2013 Weighted average [Member]
Revenue Recognition
Term of outsourcing contracts for benefit services							3 years				5 years
Term of outsourcing contracts for HR BPO services							5 years				10 years
Cash and Cash Equivalents
Operating funds in U.K.	$ 126,000,000	$ 124,000,000		£ 77,000,000
Cash and cash equivalents, restricted	88,000,000	76,000,000
Fiduciary Assets and Liabilities
Premium trust balances	3,800,000,000	4,000,000,000
Allowance for Doubtful Accounts
Allowance for doubtful accounts receivable	90,000,000	118,000,000
Fixed Assets
Fixed assets, original life, weighted-average					35 years	6 years		4 years	4 years	4 years		7 years	10 years	10 years	6 years
Goodwill and Intangible Assets
Useful life of finite-lived intangible assets							1 year				13 years					10 years
Foreign Currency
Effect of foreign exchange gains (losses) on the consolidated statements of income	3,000,000	(16,000,000)	10,000,000
Derivative (losses) gains	$ (10,000,000)	$ 3,000,000	$ (20,000,000)