Income Taxes (Details) (USD $) In Millions	3 Months Ended			6 Months Ended
	Sep. 30, 2011	Mar. 31, 2011	Mar. 31, 2010	Sep. 30, 2011
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions	$ 260	$ 200
Income Taxes Paid	120			180
Tax Adjustments, Settlements, and Unusual Provisions	45
Noncash Income Tax Expense - HCR			$ 85.1