Stock-Based Compensation Schedule of Share Repurchases (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended		20 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015
May 2014 Repurchase Program [Member] [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchased and Retired During Period, Value	$ 0	$ 97	$ 57	$ 242	$ 394
Stock Repurchased and Retired During Period, Shares	0.0	2.5	1.0	6.5	9.2
May 2015 Repurchase Program [Member] [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchased and Retired During Period, Value	$ 126	$ 0	$ 327	$ 0
Stock Repurchased and Retired During Period, Shares	1.8	0.0	4.8	0.0
Repurchase Program, Total
Equity, Class of Treasury Stock [Line Items]
Stock Repurchased and Retired During Period, Value	$ 126	$ 97	$ 384	$ 242
Stock Repurchased and Retired During Period, Shares	1.8	2.5	5.8	6.5