Cash and Cash Equivalents - Securities Purchased Under Agreements (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Abstract]
Average securities purchased under agreements to resell	$ 149,385	$ 166,205
Maximum amount outstanding at any month-end during the year	$ 450,164	$ 613,247

Securities Purchased Under Agreement to Resell, Maximum Month End Balance During Period

No definition available.

Name:	sivb_SecuritiesPurchasedUnderAgreementToResellMaximumMonthEndBalanceDuringPeriod
Namespace Prefix:	sivb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration