Valuation (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Valuation [Abstract]
Senior notes, estimated fair value					$ 86,000
Level 3
Valuation [Abstract]
Assets, Transfers out of Level 3	$ (12,357)	$ (17,260)	$ (13,411)	$ (43,094)
Assets, Transfers into Level 3	22,484	10,107	38,490	11,120
Level 3 | Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized gains (losses)	(4,700)		(400)
Level 3 | Loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized gains (losses)	4,100		10,200
Level 3 | Investment in unconsolidated entities
Valuation [Abstract]
Assets, Transfers out of Level 3	0		0
Assets, Transfers into Level 3	0		0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized gains (losses)	3,300		2,400
Level 3 | Financial Derivatives - Assets
Valuation [Abstract]
Assets, Transfers out of Level 3		0		0
Assets, Transfers into Level 3		0		0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized gains (losses)	100	(100)	(200)	(600)
Level 3 | Other secured borrowings, at fair value
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized gains (losses)	(100)	$ (400)	(32)	$ 800
Level 3 | Financial Derivatives - Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized gains (losses)	$ (200)		$ (200)