Fair Value of Financial Instruments - Summary of Estimated Fair Values of Investments and Remaining Unfunded Commitments for Each Major Category of Investments (Detail) $ in Thousands	Sep. 30, 2018 USD ($)
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Carrying Amount	$ 468,436
Fair Value	468,436
Unfunded Commitments	19,084
Venture capital and private equity fund investments \| Non-marketable securities \| Fair value accounting
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Carrying Amount	334,419
Fair Value	334,419
Unfunded Commitments	13,255
Venture capital and private equity fund investments \| Non-marketable securities \| Equity method accounting
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Carrying Amount	112,537
Fair Value	112,537
Unfunded Commitments	4,943
Debt funds \| Non-marketable securities \| Equity method accounting
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Carrying Amount	5,241
Fair Value	5,241
Unfunded Commitments	0
Other investments \| Non-marketable securities \| Equity method accounting
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Carrying Amount	16,239
Fair Value	16,239
Unfunded Commitments	$ 886

Carrying Amount, Investments, Entities that Calculate Net Asset Value, Planned Sale, Investments Not Identified, Value

No definition available.

Name:	sivb_CarryingAmountInvestmentsEntitiesThatCalculateNetAssetValuePlannedSaleInvestmentsNotIdentifiedValue
Namespace Prefix:	sivb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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.

+ References

No definition available.

+ Details

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

- Definition

The total fair value for all investments, comprising or included in the major category, of those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments) for which the entity has intentions to sell or liquidate, but the specific assets for sale or liquidation have not been identified (for example, the entity intends to sell $10,000,000 of its investments in private equity funds, but the individual investments to be sold have not been identified).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=SL6742756-110258

+ Details

Name:	us-gaap_FairValueInvestmentsEntitiesThatCalculateNetAssetValuePerSharePlannedSaleInvestmentsNotIdentifiedValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=SL6742756-110258

+ Details

Name:	us-gaap_FairValueInvestmentsEntitiesThatCalculateNetAssetValuePerShareUnfundedCommittments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	invest_InvestmentHoldingAxis=sivb_VentureCapitalAndPrivateEquityFundInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	invest_InvestmentAxis=sivb_NonmarketableSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=sivb_FairValueAccountingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_EquityMethodInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	invest_InvestmentHoldingAxis=us-gaap_DebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	invest_InvestmentHoldingAxis=us-gaap_OtherInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: