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 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

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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

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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

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

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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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) - $ / shares	1 Months Ended	3 Months Ended
Subsequent Events (Details) - $ / shares	Apr. 26, 2016	Mar. 31, 2016	Dec. 31, 2015
Subsequent events:
Dividend declared (in dollars per share)			$ 1.3
Dividend declared, date		Apr. 26, 2016
Dividend payable, date		Jun. 10, 2016
Shareholders of record, date		May 10, 2016
Subsequent event
Subsequent events:
Dividend declared (in dollars per share)	$ 1.4
Dividend per share increase (in dollars per share)	$ 0.1
Dividend per share increase (as a percent)	8.00%