Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Tax Reconciliation, Change in Deferred Tax Assets Valuation Allowance			$ 275	$ 297
Decrease in valuation allowance attributable to disposition of intangible assets				73
Income tax benefit	$ (46)	$ (71)	$ (29)	(56)
FCC License Amortization Period for Tax Purposes In Years			15 years
Unrecognized tax benefit	$ 169		$ 169		$ 163
Income Taxes Paid, Net			$ 33	$ 40