Fiduciary Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Fiduciary Assets and Liabilities [Line Items]
Interest on fiduciary funds	$ 6	$ 5
Net uncollected premiums and claims receivable and payable	7,600		$ 6,900
Consulting Segment
Fiduciary Assets and Liabilities [Line Items]
Interest on fiduciary funds	$ 1	$ 1