Other Commitments and Contingent Liabilities (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2015
Loss Contingencies [Line Items]
Claims and litigation charges	$ 150	$ 68	$ 72
Anti-Kickback Claim [Member]
Loss Contingencies [Line Items]
Loss Contingency Number of States Filed On Behalf Of	21
Loss Contingency Number of Relators	2
Loss Contingency Number of Additional Defendants	5
Controlled Substance Investigation [Member]
Loss Contingencies [Line Items]
Claims and litigation charges	150			150
Claims and litigation charges, net of tax	150
Environmental Litigation [Member]
Loss Contingencies [Line Items]
Chemical conditions sites, number	6
Remediation costs	7			7
Hazardous substance sites, number	14
Estimated environmental assessment and cleanup costs	70
Estimated loss	22			22
Environmental Litigation [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Site Contingency, Time Frame of Disbursements	2015-04-01
Environmental Litigation [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Site Contingency, Time Frame of Disbursements	2035-03-31
Average Wholesale Price Litigation [Member]
Loss Contingencies [Line Items]
Claims and litigation charges	$ 0	$ 68	$ 72