Segment and Geographic Information 1 (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Jun. 30, 2011	Jun. 30, 2010
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	$ 1,163	$ 1,069
Expenses	746	705
Segment profit	342	321
Segment operating margin	36.00%	34.00%
Depreciation and amortization	97	89
Segment profit	342	321
Share-based compensation expense before income tax	25	19
Other unallocated operating expenses (gains), net	8	(14)
Interest expense, net	9	13
Income from continuing operations before income taxes	333	308
Mainframe Solutions [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	646	615
Expenses	276	280
Segment profit	370	335
Segment operating margin	57.00%	54.00%
Segment profit	370	335
Mainframe Solutions [Member] \| Depreciation And Amortization Of Developed Software [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Depreciation and amortization	24	26
Enterprise Solutions [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	427	376
Expenses	382	351
Segment profit	45	25
Segment operating margin	11.00%	7.00%
Segment profit	45	25
Enterprise Solutions [Member] \| Depreciation And Amortization Of Developed Software [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Depreciation and amortization	31	25
Services [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	90	78
Expenses	88	74
Segment profit	2	4
Segment operating margin	2.00%	5.00%
Segment profit	2	4
Services [Member] \| Depreciation And Amortization Of Developed Software [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Depreciation and amortization	0	0
Total Reportable Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment profit	417	364
Segment profit	417	364
Depreciation And Amortization Of Developed Software [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Depreciation and amortization	55	51
Purchased software products [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Depreciation and amortization	23	22
Other intangible assets subject to amortization [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Depreciation and amortization	$ 19	$ 16

Segment expenses that include costs that are controllable by segment managers (direct expenses) and allocations of shared and indirect costs.

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Operating margin.

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- Definition

Other operating expense (gains) not allocated to the Company's reporting segments.

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-SubTopic 10
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
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- Definition

The net amount of operating interest income (expense).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
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-Section 04
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The net result for the period of deducting operating expenses from operating revenues.

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Aggregate revenue recognized during the period (derived from goods sold, services rendered, insurance premiums, or other activities that constitute an entity's earning process). For financial services companies, also includes investment and interest income, and sales and trading gains.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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