Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Tax Reconciliation, Change in Deferred Tax Assets Valuation Allowance			$ 647	$ 797
Decrease in valuation allowance attributable to disposition of intangible assets				73
Income tax benefit	$ (97)	$ 657	$ (126)	601
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)		$ 1,900
FCC License Amortization Period for Tax Purposes In Years			15 years
Unrecognized tax benefit	$ 167		$ 167		$ 163
Income Taxes Paid, Net			$ 34	$ 36