Represents the increase in the dividend declared over the prior period.

No definition available.

Name:	ibm_CommonStockDividendsPerShareDeclaredIncrease
Namespace Prefix:	ibm_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage increase in the dividend declared over the prior period.

+ References

No definition available.

+ Details

Name:	ibm_CommonStockDividendsPerShareDeclaredPercentageIncrease
Namespace Prefix:	ibm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Aggregate dividends declared during the period for each share of common stock outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

+ Details

Name:	us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the declared dividend will be paid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

+ Details

Name:	us-gaap_DividendPayableDateToBePaidDayMonthAndYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the dividend to be paid was declared, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_DividendsPayableDateDeclaredDayMonthAndYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the holder must own the stock to be entitled to the dividend, in CCYY-MM-DD format.

+ References

No definition available.

+ Details

Name:	us-gaap_DividendsPayableDateOfRecordDayMonthAndYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Subsequent Events (Details) (USD $)	3 Months Ended	1 Months Ended	3 Months Ended
Subsequent Events (Details) (USD $)	Dec. 31, 2014	Apr. 28, 2015	Mar. 31, 2015
Subsequent events:
Dividend declared (in dollars per share)	$ 1.1
Subsequent event
Subsequent events:
Dividend declared (in dollars per share)		$ 1.3
Dividend declared, date			Apr. 28, 2015
Dividend payable, date			Jun. 10, 2015
Shareholders of record, date			May 08, 2015
Dividend per share increase (in dollars per share)		$ 0.2
Dividend per share increase (as a percent)		18.00%