Off-Balance Sheet Arrangements, Guarantees and Other Commitments - Total Capital Commitments, Unfunded Capital Commitments, and Our Ownership in Each Fund (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) Investment	Dec. 31, 2019
Other Commitments [Line Items]
SVBFG Unfunded Commitments	$ 4,261
Capital Preferred Return Fund, LP
Other Commitments [Line Items]
SVBFG Unfunded Commitments	1,516
Growth Partners, LP
Other Commitments [Line Items]
SVBFG Unfunded Commitments	2,549
Strategic Investors Fund, LP
Other Commitments [Line Items]
SVBFG Unfunded Commitments	$ 196
Consolidated venture capital and private equity fund investments | CP II, LP | Non-marketable securities | Direct ownership interest
Other Commitments [Line Items]
SVBFG Ownership interest percentage	1.30%
Consolidated venture capital and private equity fund investments | CP II, LP | Non-marketable securities | Indirect ownership interest
Other Commitments [Line Items]
SVBFG Ownership interest percentage	3.80%
Upper Limit
Other Commitments [Line Items]
SVBFG Ownership interest percentage	5.00%
Equity method accounting | Consolidated venture capital and private equity fund investments | CP II, LP | Non-marketable securities
Other Commitments [Line Items]
SVBFG Ownership interest percentage	5.10%	5.10%
Equity method accounting | Consolidated venture capital and private equity fund investments | CP II, LP | Non-marketable securities | Direct ownership interest
Other Commitments [Line Items]
SVBFG Ownership interest percentage	1.30%
Equity method accounting | Consolidated venture capital and private equity fund investments | CP II, LP | Non-marketable securities | Indirect ownership interest
Other Commitments [Line Items]
SVBFG Ownership interest percentage	3.80%
Equity method accounting | Consolidated venture capital and private equity fund investments | Strategic Investors Fund II, LP | Non-marketable securities
Other Commitments [Line Items]
SVBFG Ownership interest percentage	8.60%	8.60%
Equity method accounting | Consolidated venture capital and private equity fund investments | Strategic Investors Fund III, LP | Non-marketable securities
Other Commitments [Line Items]
SVBFG Ownership interest percentage	5.90%	5.90%
Equity method accounting | Consolidated venture capital and private equity fund investments | Strategic Investors Fund IV, LP | Non-marketable securities
Other Commitments [Line Items]
SVBFG Ownership interest percentage	5.00%	5.00%
Equity method accounting | Consolidated venture capital and private equity fund investments | Other fund investments | Non-marketable securities
Other Commitments [Line Items]
Number of other funds with investment commitments | Investment	168
Equity method accounting | Upper Limit | Consolidated venture capital and private equity fund investments | Other fund investments | Non-marketable securities
Other Commitments [Line Items]
SVBFG Ownership interest percentage	5.00%
Parent Company
Other Commitments [Line Items]
SVBFG Capital Commitments	$ 457,878
SVBFG Unfunded Commitments	22,083
Parent Company | CP II, LP
Other Commitments [Line Items]
SVBFG Capital Commitments	1,200
SVBFG Unfunded Commitments	$ 162
SVBFG Ownership interest percentage	5.10%
Parent Company | Strategic Investors Fund II, LP
Other Commitments [Line Items]
SVBFG Capital Commitments	$ 15,000
SVBFG Unfunded Commitments	$ 1,050
SVBFG Ownership interest percentage	8.60%
Parent Company | Strategic Investors Fund III, LP
Other Commitments [Line Items]
SVBFG Capital Commitments	$ 15,000
SVBFG Unfunded Commitments	$ 1,275
SVBFG Ownership interest percentage	5.90%
Parent Company | Strategic Investors Fund IV, LP
Other Commitments [Line Items]
SVBFG Capital Commitments	$ 12,239
SVBFG Unfunded Commitments	$ 2,325
SVBFG Ownership interest percentage	5.00%
Parent Company | Strategic Investors Fund V funds
Other Commitments [Line Items]
SVBFG Capital Commitments	$ 515
SVBFG Unfunded Commitments	131
Parent Company | Other venture capital and private equity fund investments
Other Commitments [Line Items]
SVBFG Capital Commitments	25,232
SVBFG Unfunded Commitments	5,566
Parent Company | Debt funds (equity method accounting)
Other Commitments [Line Items]
SVBFG Capital Commitments	58,733
SVBFG Unfunded Commitments	211
Parent Company | Other fund investments
Other Commitments [Line Items]
SVBFG Capital Commitments	277,301
SVBFG Unfunded Commitments	9,335
Parent Company | Capital Preferred Return Fund, LP
Other Commitments [Line Items]
SVBFG Capital Commitments	12,688
SVBFG Unfunded Commitments	$ 0
SVBFG Ownership interest percentage	20.00%
Parent Company | Growth Partners, LP
Other Commitments [Line Items]
SVBFG Capital Commitments	$ 24,670
SVBFG Unfunded Commitments	$ 1,340
SVBFG Ownership interest percentage	33.00%
Parent Company | Strategic Investors Fund, LP
Other Commitments [Line Items]
SVBFG Capital Commitments	$ 15,300
SVBFG Unfunded Commitments	$ 688
SVBFG Ownership interest percentage	12.60%