Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Activity in Allowance for Loan Losses Broken out by Portfolio Segment (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	$ 255,024	$ 225,366	$ 217,613
Charge-offs	(67,917)	(66,682)	(96,857)
Recoveries	11,636	8,538	12,212
Provision for loan losses	84,292	85,939	95,697
Allowance for Loan and Lease Losses, Foreign Currency Translation	(2,132)	1,863	(3,299)
Ending Balance	280,903	255,024	225,366
Software and internet
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance		97,388	103,045
Charge-offs			(68,784)
Recoveries			7,278
Provision for loan losses			58,350
Ending Balance			97,388
Hardware
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance		31,166	23,085
Charge-offs			(13,233)
Recoveries			1,667
Provision for loan losses			20,851
Ending Balance			31,166
Private equity/venture capital
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance		50,299	35,282
Charge-offs			0
Recoveries			0
Provision for loan losses			15,114
Ending Balance			50,299
Life science/healthcare
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance		25,446	36,576
Charge-offs			(9,693)
Recoveries			1,129
Provision for loan losses			(2,543)
Ending Balance			25,446
Premium wine
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance		4,115	5,205
Charge-offs			0
Recoveries			0
Provision for loan losses			(1,260)
Ending Balance			4,115
Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance		4,768	4,252
Charge-offs			(5,045)
Recoveries			1,880
Provision for loan losses			3,373
Ending Balance			4,768
Commercial loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	238,583	213,182	207,445
Charge-offs	(67,628)	(65,115)	(96,755)
Recoveries	11,149	7,175	11,954
Provision for loan losses	80,953	81,553	93,885
Ending Balance	260,966	238,583	213,182
Commercial loans \| Software and internet
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	96,104	97,388
Charge-offs	(42,315)	(45,012)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	5,664	4,649
Provision for loan losses	45,068	38,462
Allowance for Loan and Lease Losses, Foreign Currency Translation	(954)	617	(2,501)
Ending Balance	103,567	96,104	97,388
Commercial loans \| Hardware
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	27,614	31,166
Charge-offs	(16,148)	(10,414)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	1,849	487
Provision for loan losses	6,555	6,051
Allowance for Loan and Lease Losses, Foreign Currency Translation	(145)	324	(1,204)
Ending Balance	19,725	27,614	31,166
Commercial loans \| Private equity/venture capital
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	82,468	50,299
Charge-offs	(112)	(323)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	13	0
Provision for loan losses	16,485	31,625
Allowance for Loan and Lease Losses, Foreign Currency Translation	(273)	867	(97)
Ending Balance	98,581	82,468	50,299
Commercial loans \| Life science/healthcare
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	24,924	25,446
Charge-offs	(6,662)	(8,210)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	348	189
Provision for loan losses	14,347	7,414
Allowance for Loan and Lease Losses, Foreign Currency Translation	(777)	85	(23)
Ending Balance	32,180	24,924	25,446
Commercial loans \| Premium wine
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	3,532	4,115
Charge-offs	0	0
Allowance for Loan and Lease Loss, Recovery of Bad Debts	0	0
Provision for loan losses	(182)	(540)
Allowance for Loan and Lease Losses, Foreign Currency Translation	5	(43)	170
Ending Balance	3,355	3,532	4,115
Commercial loans \| Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	3,941	4,768
Charge-offs	(2,391)	(1,156)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	3,275	1,850
Provision for loan losses	(1,320)	(1,459)
Allowance for Loan and Lease Losses, Foreign Currency Translation	53	(62)	308
Ending Balance	3,558	3,941	4,768
Commercial loans \| Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan and Lease Losses, Foreign Currency Translation	(2,091)	1,788	(3,347)
Consumer loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	16,441	12,184	10,168
Charge-offs			(102)
Recoveries			258
Provision for loan losses			1,812
Ending Balance	19,937	16,441	12,184
Consumer loans \| Consumer Loan
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	16,441	12,184
Charge-offs	(289)	(1,567)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	487	1,363
Provision for loan losses	3,339	4,386
Allowance for Loan and Lease Losses, Foreign Currency Translation	$ (41)	75	48
Ending Balance		$ 16,441	$ 12,184

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Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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Amount of gain (loss) from converting allowance reserve for credit loss to currency of reporting entity from amount denominated or measured in a different currency, which decreases (increases) the allowance for loan and lease losses.

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount of expense related to loss from loan transactions.

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