Subsequent Events (Details) - Subsequent Event - Boston Private $ / shares in Units, $ in Billions	Jul. 01, 2021 USD ($) $ / shares shares
Subsequent Event [Line Items]
Consideration transferred in acquisition | $	$ 1.2
Number of shares of SIVB common stock that each share of Boston Private common stock was converted	0.228
Cash paid for each share of Boston Private common stock | $ / shares	$ 2.10
Shares of common stock issued for acquisition	1,900,000
Additional number of SIVB shares registered issuable upon the exercise, vesting or settlement of converted legacy Boston Private equity awards	99,000