Principles of Consolidation And Other Matters (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Operating funds related to regulatory requirements or as collateral under captive insurance arrangements	$ 188,000,000		$ 188,000,000
Equity method investments lag period			3 months
Investment income (loss)	$ 1,000,000	$ 3,000,000	$ (2,000,000)	$ 5,000,000
Effective tax rate	29.50%	27.90%	29.00%	28.60%
Unrecognized tax benefits	$ 70,000,000		$ 70,000,000		$ 74,000,000
Minimum
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Reasonably possible decrease in unrecognized tax benefits	0		0
Maximum
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Reasonably possible decrease in unrecognized tax benefits	$ 7,000,000		$ 7,000,000