Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Income Tax Reconciliation, Change in Deferred Tax Assets Valuation Allowance	$ 142	$ 22
Income tax benefit	$ (56)	17
FCC License Amortization Period for Tax Purposes In Years	15 years
Unrecognized tax benefit	$ 167		$ 166
Income Taxes Paid, Net	$ 21	$ 26