Stockholders' Equity and EPS - Common Stock (Details) - USD ($) $ / shares in Units, $ in Millions	Aug. 12, 2021	Jul. 01, 2021	Apr. 14, 2021	Mar. 22, 2021	Dec. 31, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Common stock, shares, issued					58,748,469	51,888,463
Boston Private
Class of Stock [Line Items]
Number of shares of SIVB common stock that each share of Boston Private common stock was converted (in shares)		0.0228
Common Stock
Class of Stock [Line Items]
Common stock, shares, issued	2,227,000		300,000	2,000,000
Price per share (usd per share)	$ 564.00			$ 500.00
Consideration received in sale of stock	$ 1,200		$ 146	$ 972
Common Stock | Boston Private
Class of Stock [Line Items]
Issuance of common stock in acquisition		1,887,981
Number of shares of SIVB common stock that each share of Boston Private common stock was converted (in shares)		0.0228