Net Income (Loss) Per Share (Computation Of Basic Earnings And Diluted Earnings Per Share) (Details) (USD $)
In Millions, except Per Share data, unless otherwise specified
 3 Months Ended 12 Months Ended
Mar. 31, 2015
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2015
Mar. 31, 2014
Mar. 31, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]                      
Net income (loss) $ 395 [1] $ 142 $ 3 [1] $ 335 [1] $ 367 [2] $ (308) [3] $ (273) [4] $ 222 [5] $ 875 $ 8 $ 98
Weighted-average common stock outstanding - basic                 311 308 310
Dilutive potential common shares                 9 8 3
Weighted-average common stock outstanding - diluted                 325 316 313
Basic $ 1.27 $ 0.46 $ 0.01 $ 1.07 $ 1.18 $ (1.00) $ (0.89) $ 0.73 $ 2.81 $ 0.03 $ 0.32
Diluted $ 1.19 $ 0.44 $ 0.01 $ 1.04 $ 1.15 $ (1.00) $ (0.89) $ 0.71 $ 2.69 $ 0.03 $ 0.31
Convertible Debt                      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]                      
Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants                 4 0 0
Warrant [Member]                      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]                      
Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants                 1 0 0
[1] Net income includes $(1) million of acquisition-related contingent consideration, of which is pre-tax amounts.
[2] Net income includes restructuring charges of $1 million and $2 million of acquisition-related contingent consideration, both of which are pre-tax amounts.
[3] Net loss includes pre-tax restructuring charges of $(1) million.
[4] Net loss includes restructuring charges of $(2) million and $(44) million of acquisition-related contingent consideration, both of which are pre-tax amounts.
[5] Net income includes restructuring charges of $1 million and $7 million of acquisition-related contingent consideration, both of which are pre-tax amounts.