Fiduciary Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Fiduciary Assets and Liabilities [Line Items]
Interest on fiduciary funds (less than)	$ 8	$ 6	$ 20	$ 16
Net uncollected premiums and claims receivable and payable	7,000		7,000		$ 6,900
Consulting Segment
Fiduciary Assets and Liabilities [Line Items]
Interest on fiduciary funds (less than)	$ 1	$ 1	$ 2	$ 3