Property and Equipment, net (Schedule Of Property And Equipment, Net) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	$ 2,624	$ 2,350
Accumulated depreciation and amortization	(1,313)	(1,079)
Property and Equipment, net	$ 1,311	1,271	$ 1,247
Buildings [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	30 years
Property and Equipment, gross	$ 823	805
Computer Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	$ 849	697
Computer Equipment and Software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	3 years
Computer Equipment and Software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	8 years
Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	$ 431	384
Furniture and Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Furniture and Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	9 years
Land [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	$ 23	23
Leasehold Land [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	63	63
Capital Work-in-Progress [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	169	115
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	$ 266	$ 263