Fiduciary Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Fiduciary Assets and Liabilities [Line Items]
Interest on fiduciary funds (less than)	$ 6	$ 5	$ 12	$ 10
Net uncollected premiums and claims receivable and payable	7,800		7,800		$ 6,900
Consulting Segment
Fiduciary Assets and Liabilities [Line Items]
Interest on fiduciary funds (less than)	$ 1	$ 1	$ 1	$ 2