Segment Information (Narrative) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Revenue, Major Customer and Geographic Information [Line Items]
Revenue, Net	$ 1,582,000,000	$ 1,160,000,000	$ 959,000,000	$ 1,449,000,000	$ 1,527,000,000	$ 1,149,000,000	$ 898,000,000	$ 1,271,000,000	$ 5,150,000,000	$ 4,845,000,000	$ 4,396,000,000
Entity Wide Revenue By Major Customer Percent Of Revenue Did Not Exceed Ten Percent									10.00%
Sales Revenue, Goods, Net [Member] | Customer Concentration Risk [Member] | Sony [Domain]
Revenue, Major Customer and Geographic Information [Line Items]
Entity Wide Revenue By Major Customer Percent Of Revenue									27.00%	19.00%	16.00%
Sales Revenue, Goods, Net [Member] | Customer Concentration Risk [Member] | Microsoft [Member]
Revenue, Major Customer and Geographic Information [Line Items]
Entity Wide Revenue By Major Customer Percent Of Revenue									16.00%	17.00%	14.00%
Switzerland [Member]
Revenue, Major Customer and Geographic Information [Line Items]
Revenue, Net									$ 2,272,000,000	$ 1,886,000,000	$ 1,643,000,000
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries, Percentage									44.00%	39.00%	37.00%
United States [Member]
Revenue, Major Customer and Geographic Information [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Entity's Country of Domicile									99.00%