Valuation (Narrative) (Details) - Level 3 - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized gains (losses)	$ 9,300	$ (4,700)	$ (56,300)	$ (400)
Loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized gains (losses)	14,200	4,100	12	10,200
Investment in unconsolidated entities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized gains (losses)	11,300	3,300	10,200	2,400
Financial Derivatives - Assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized gains (losses)	(300)	100	600	(200)
Other secured borrowings, at fair value
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized gains (losses)	(5,200)	(100)	(6,600)	(32)
Financial Derivatives - Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized gains (losses)	$ (11)	$ (200)	$ (100)	$ (200)