Loans and Leases - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) loan	Dec. 31, 2015 USD ($) loan	Dec. 31, 2014 USD ($)
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, allowance for losses	$ 53,000	$ 46,000
Loans and leases pledged as collateral	$ 1,500,000	$ 2,500,000
Loans modified in troubled debt restructurings | loan	0	0
Provision for loan losses	$ 10,000	$ 12,000	$ 10,000
Charge-offs	(3,000)	$ (4,000)	$ 0
Commercial and Financial | Senior Secured Bank Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, allowance for losses	$ 195
Total Institutional
Financing Receivable, Recorded Investment [Line Items]
Loans more than 90 days past due | loan	1
Total CRE
Financing Receivable, Recorded Investment [Line Items]
Loans more than 90 days past due | loan	0