Per Share Data	9 Months Ended
Dec. 31, 2017
Earnings Per Share [Abstract]
Per Share Data	Per Share Data Basic net income (loss) per common share is calculated by dividing net income (loss) by the weighted average number of common shares outstanding during the period. Diluted net income (loss) per common share adjusts basic net income (loss) per common share, computed using the treasury stock method, for the effects of potentially dilutive common shares, if the effect is not antidilutive. As of the three-month period ended December 31, 2017, the computation of diluted net income (loss) per common share includes the effect of dilutive securities consisting of approximately 47 million options and restricted stock units, in addition to 13 million shares attributable to warrants, of which 9 million relate to the warrant held by SoftBank. As of the nine-month period ended December 31, 2017, the computation of diluted net income (loss) per common share includes the effect of dilutive securities consisting of approximately 61 million options and restricted stock units, in addition to 21 million shares attributable to warrants, of which 17 million relate to the warrant held by SoftBank. As of both the three and nine-month periods ended December 31, 2017, outstanding options to purchase shares totaling 6 million were not included in the computation of diluted net income (loss) per common share because to do so would have been antidilutive. Outstanding options and restricted stock units (exclusive of participating securities) that had no effect on our computation of dilutive weighted average number of shares outstanding as their effect would have been antidilutive were approximately 118 million shares as of the three and nine-month periods ended December 31, 2016, in addition to 62 million total shares issuable under warrants, of which 55 million relate to shares issuable under the warrant held by SoftBank. The warrant was issued to SoftBank at the close of the merger with SoftBank and is exercisable at $5.25 per share at the option of SoftBank, in whole or in part, at any time on or prior to July 10, 2018.

Per Share Data

Basic net income (loss) per common share is calculated by dividing net income (loss) by the weighted average number of common shares outstanding during the period. Diluted net income (loss) per common share adjusts basic net income (loss) per common share, computed using the treasury stock method, for the effects of potentially dilutive common shares, if the effect is not antidilutive. As of the three-month period ended December 31, 2017, the computation of diluted net income (loss) per common share includes the effect of dilutive securities consisting of approximately 47 million options and restricted stock units, in addition to 13 million shares attributable to warrants, of which 9 million relate to the warrant held by SoftBank. As of the nine-month period ended December 31, 2017, the computation of diluted net income (loss) per common share includes the effect of dilutive securities consisting of approximately 61 million options and restricted stock units, in addition to 21 million shares attributable to warrants, of which 17 million relate to the warrant held by SoftBank. As of both the three and nine-month periods ended December 31, 2017, outstanding options to purchase shares totaling 6 million were not included in the computation of diluted net income (loss) per common share because to do so would have been antidilutive. Outstanding options and restricted stock units (exclusive of participating securities) that had no effect on our computation of dilutive weighted average number of shares outstanding as their effect would have been antidilutive were approximately 118 million shares as of the three and nine-month periods ended December 31, 2016, in addition to 62 million total shares issuable under warrants, of which 55 million relate to shares issuable under the warrant held by SoftBank. The warrant was issued to SoftBank at the close of the merger with SoftBank and is exercisable at $5.25 per share at the option of SoftBank, in whole or in part, at any time on or prior to July 10, 2018.