Off-Balance Sheet Arrangements, Guarantees and Other Commitments - Total Capital Commitments, Unfunded Capital Commitments, and Our Ownership in Each Fund (Details) $ in Thousands	3 Months Ended
	Sep. 30, 2020 USD ($)
Venture Capital and Private Equity Fund Investments [Line Items]
SVBFG Unfunded Commitments	$ 4,406
Capital Preferred Return Fund, LP
Venture Capital and Private Equity Fund Investments [Line Items]
SVBFG Unfunded Commitments	1,517
Growth Partners, LP
Venture Capital and Private Equity Fund Investments [Line Items]
SVBFG Unfunded Commitments	2,513
Strategic Investors Fund, LP
Venture Capital and Private Equity Fund Investments [Line Items]
SVBFG Unfunded Commitments	376
Parent Company
Venture Capital and Private Equity Fund Investments [Line Items]
SVBFG Capital Commitments	464,881
SVBFG Unfunded Commitments	19,353
Parent Company | CP II, LP
Venture Capital and Private Equity Fund Investments [Line Items]
SVBFG Capital Commitments	1,200
SVBFG Unfunded Commitments	$ 162
SVBFG Ownership of each Fund	5.10%
Parent Company | Strategic Investors Fund II, LP
Venture Capital and Private Equity Fund Investments [Line Items]
SVBFG Capital Commitments	$ 15,000
SVBFG Unfunded Commitments	$ 1,050
SVBFG Ownership of each Fund	8.60%
Parent Company | Strategic Investors Fund III, LP
Venture Capital and Private Equity Fund Investments [Line Items]
SVBFG Capital Commitments	$ 15,000
SVBFG Unfunded Commitments	$ 1,275
SVBFG Ownership of each Fund	5.90%
Parent Company | Strategic Investors Fund IV, LP
Venture Capital and Private Equity Fund Investments [Line Items]
SVBFG Capital Commitments	$ 12,239
SVBFG Unfunded Commitments	$ 2,325
SVBFG Ownership of each Fund	5.00%
Parent Company | Strategic Investors Fund V funds
Venture Capital and Private Equity Fund Investments [Line Items]
SVBFG Capital Commitments	$ 515
SVBFG Unfunded Commitments	131
Parent Company | Other venture capital and private equity fund investments
Venture Capital and Private Equity Fund Investments [Line Items]
SVBFG Capital Commitments	25,197
SVBFG Unfunded Commitments	6,258
Parent Company | Debt funds (equity method accounting)
Venture Capital and Private Equity Fund Investments [Line Items]
SVBFG Capital Commitments	58,733
SVBFG Unfunded Commitments	240
Parent Company | Other fund investments
Venture Capital and Private Equity Fund Investments [Line Items]
SVBFG Capital Commitments	278,339
SVBFG Unfunded Commitments	5,614
Parent Company | CP I, LP
Venture Capital and Private Equity Fund Investments [Line Items]
SVBFG Capital Commitments	6,000
SVBFG Unfunded Commitments	$ 270
SVBFG Ownership of each Fund	10.70%
Parent Company | Capital Preferred Return Fund, LP
Venture Capital and Private Equity Fund Investments [Line Items]
SVBFG Capital Commitments	$ 12,688
SVBFG Unfunded Commitments	$ 0
SVBFG Ownership of each Fund	20.00%
Parent Company | Growth Partners, LP
Venture Capital and Private Equity Fund Investments [Line Items]
SVBFG Capital Commitments	$ 24,670
SVBFG Unfunded Commitments	$ 1,340
SVBFG Ownership of each Fund	33.00%
Parent Company | Strategic Investors Fund, LP
Venture Capital and Private Equity Fund Investments [Line Items]
SVBFG Capital Commitments	$ 15,300
SVBFG Unfunded Commitments	$ 688
SVBFG Ownership of each Fund	12.60%