Debt (Schedule Of Outstanding Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Sep. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	May. 31, 2014
Debt Instrument [Line Items]
Current portion of long-term debt	$ 12			$ 11
Long-term debt, current and noncurrent	4,414			3,379
Long-term debt and capital lease obligations	4,402			3,368
5.875% Senior Debt Obligations Due 2033
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 297			297
Interest rate	5.875%
5.375% Senior Debt Obligations Due 2014
Debt Instrument [Line Items]
Interest rate	5.375%					5.375%
5.75% Senior Debt Obligations Due 2015
Debt Instrument [Line Items]
Interest rate	5.75%
2.30% Senior Debt Obligations Due 2017
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 249			249
Interest rate	2.30%
9.25% Senior Debt Obligations Due 2019
Debt Instrument [Line Items]
Interest rate	9.25%
4.80% Senior Debt Obligations Due 2021
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 497			497
Interest rate	4.80%
2.55% Senior Debt Obligations Due 2018
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 249			249
Interest rate	2.55%
4.05% Senior Debt Obligations Due 2023
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 248			247
Interest rate	4.05%
3.50% Senior Debt Obligations Due 2024
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 595			594
Interest rate	3.50%					3.50%
2.35% Senior Debt Obligations Due 2019
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 298			298
Interest rate	2.35%				2.35%
3.50% Senior Debt Obligations Due 2025
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 495			494
Interest rate	3.50%				3.50%
3.75% Senior Debt Obligations Due 2026
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 595			0
Interest rate	3.75%	3.75%
2.35% Senior Debt Obligations Due 2020
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 496			0
Interest rate	2.35%		2.35%
Mortgage Due 2035
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 393			403
Interest rate	5.70%
Three-Year Delayed Draw Term Loan Facility
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 0			50
Other Debt Instruments
Debt Instrument [Line Items]
Long-term debt, current and noncurrent	$ 2			$ 1