Description Of Business And Summary Of Significant Accounting Policies (Recently Adopted Accounting Standards) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2017	Mar. 31, 2018
Minimum [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Cumulative Effect on Retained Earnings, before Tax		$ 550
Maximum [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Cumulative Effect on Retained Earnings, before Tax		$ 650
Accounting Standards Update 2016-09 [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax	$ 8