Valuation (Fair Value Measurement Using Significant Unobservable Inputs) (Details) - Level 3 [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	$ 519,124	$ 535,274	$ 493,541	$ 638,486
Assets, Accreted Discounts/Amortized Premiums	(4,129)	(4,911)	(12,918)	(7,811)
Assets, Realized Gain (Loss)	1,217	8,908	5,730	23,829
Assets, Change In Net Unrealized Gain/(Loss)	8,012	(13,353)	(1,860)	(22,719)
Assets, Purchases	199,211	88,369	420,365	347,139
Assets, Sales	(234,819)	(117,751)	(418,307)	(439,308)
Assets, Transfers into Level 3	1,517	20,154	8,360	9,667
Assets, Transfers out of Level 3	(13,815)	(14,294)	(18,593)	(46,887)
Assets, Ending Balance	476,318	502,396	476,318	502,396
Liabilities, Begining Balance	(11,509)	(2,851)	(6,159)	(1,013)
Liabilities, Accreted Discounts/Amortized Premiums	0	(3)	(8)	(5)
Liabilities, Realized Gain/(Loss)	(2,247)	836	(6,160)	1,147
Liabilities, Change In Net Unrealized Gain/(Loss)	(119)	(2,349)	3,508	(4,285)
Liabilities Purchases/Payments	22,911	(715)	38,853	(968)
Liabilities, Sales/Issuance	(49,858)	33	(70,856)	75
Liabilities, Transfers into Level 3	0	0	0	0
Liabilities, Transfers out of Level 3	0	0	0	0
Liabilities, Ending Balance	(40,822)	(5,049)	(40,822)	(5,049)
Change in net unrealized gain (loss) on investments Level 3 Held At End of Period	600	(11,800)	(10,400)	(21,800)
Unrealized Gain (Loss) On Investments Sold Short, Level 3, Held At End Of Period	(34)		(300)
Change in net unrealized gain (loss) in financial derivative assets Level 3 Held At End of Period	400	(300)	(300)	(71)
Change in net unrealized Gain (Loss) on financial derivative liabilities Level 3 Held At End of Period	(1,100)	(1,300)	(1,200)	(3,000)
Change in net unrealized gain (loss) in securitized debt Level 3 Held At End of Period		1		21
Change in net unrealized Gain (Loss) On Guarantees Level 3 Held At End Of Period	200	(1,200)	700	(1,200)
Securitized Debt [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Liabilities, Begining Balance		(655)		(774)
Liabilities, Accreted Discounts/Amortized Premiums		(3)		(5)
Liabilities, Realized Gain/(Loss)		0		0
Liabilities, Change In Net Unrealized Gain/(Loss)		1		21
Liabilities, Payments		154		255
Liabilities, Issuances		0		0
Liabilities, Transfers into Level 3		0		0
Liabilities, Transfers out of Level 3		0		0
Liabilities, Ending Balance		(503)		(503)
Guarantees [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Liabilities, Begining Balance	(312)	(13)	(828)	0
Liabilities, Accreted Discounts/Amortized Premiums	0	0	0	0
Liabilities, Realized Gain/(Loss)	0	0	0	0
Liabilities, Change In Net Unrealized Gain/(Loss)	162	(1,216)	678	(1,229)
Liabilities, Payments	0	0	0	0
Liabilities, Issuances	0	0	0	0
Liabilities, Transfers into Level 3	0	0	0	0
Liabilities, Transfers out of Level 3	0	0	0	0
Liabilities, Ending Balance	(150)	(1,229)	(150)	(1,229)
Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	512,132	525,478	486,974	626,999
Assets, Accreted Discounts/Amortized Premiums	(4,129)	(4,911)	(12,918)	(7,811)
Assets, Realized Gain (Loss)	(2,609)	8,411	1,593	24,210
Assets, Change In Net Unrealized Gain/(Loss)	8,861	(12,972)	(1,495)	(23,287)
Assets, Purchases	190,706	88,341	411,425	347,065
Assets, Sales	(229,984)	(117,014)	(412,667)	(436,763)
Assets, Transfers into Level 3	1,517	20,154	8,360	9,667
Assets, Transfers out of Level 3	(13,815)	(14,294)	(18,593)	(46,887)
Assets, Ending Balance	462,679	493,193	462,679	493,193
Investments [Member] | Agency residential mortgage-backed securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	20,506	30,385	24,918	31,385
Assets, Accreted Discounts/Amortized Premiums	(1,821)	(2,249)	(5,766)	(6,196)
Assets, Realized Gain (Loss)	(77)	0	(168)	472
Assets, Change In Net Unrealized Gain/(Loss)	(169)	(1,135)	(849)	373
Assets, Purchases	1,385	1,354	1,689	8,860
Assets, Sales	0	0	0	(6,539)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	19,824	28,355	19,824	28,355
Investments [Member] | Private Label Residential Mortgage-Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	112,511	160,046	116,435	274,369
Assets, Accreted Discounts/Amortized Premiums	256	2,682	1,518	7,524
Assets, Realized Gain (Loss)	(958)	4,139	(1,305)	16,855
Assets, Change In Net Unrealized Gain/(Loss)	6,086	(5,191)	2,995	(11,589)
Assets, Purchases	0	10,138	7,439	64,366
Assets, Sales	(23,652)	(27,217)	(34,904)	(163,848)
Assets, Transfers into Level 3	1,517	20,154	8,360	9,667
Assets, Transfers out of Level 3	(13,815)	(14,294)	(18,593)	(46,887)
Assets, Ending Balance	81,945	150,457	81,945	150,457
Investments [Member] | Private Label Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	34,942	49,834	34,145	53,311
Assets, Accreted Discounts/Amortized Premiums	429	579	1,315	2,507
Assets, Realized Gain (Loss)	87	25	409	549
Assets, Change In Net Unrealized Gain/(Loss)	(292)	(151)	(4,132)	(2,844)
Assets, Purchases	5,335	1,250	13,179	21,382
Assets, Sales	(3,556)	(9,022)	(7,971)	(32,390)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	36,945	42,515	36,945	42,515
Investments [Member] | Commercial Mortgage Loans [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	49,466	55,310	66,399	28,309
Assets, Accreted Discounts/Amortized Premiums	801	(2)	2,073	1,273
Assets, Realized Gain (Loss)	72	543	254	542
Assets, Change In Net Unrealized Gain/(Loss)	(1,140)	(192)	(917)	(812)
Assets, Purchases	13,226	4,305	26,650	55,115
Assets, Sales	(5,456)	(5,344)	(37,490)	(29,807)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	56,969	54,620	56,969	54,620
Investments [Member] | Residential Mortgage Loans [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	46,649	20,929	22,089	27,482
Assets, Accreted Discounts/Amortized Premiums	67	279	315	1,127
Assets, Realized Gain (Loss)	(78)	714	787	2,378
Assets, Change In Net Unrealized Gain/(Loss)	(66)	(9)	61	(80)
Assets, Purchases	24,002	3,902	56,068	13,660
Assets, Sales	(26,499)	(8,156)	(35,245)	(26,908)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	44,075	17,659	44,075	17,659
Investments [Member] | Collateralized Loan Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	33,109	98,388	45,974	123,338
Assets, Accreted Discounts/Amortized Premiums	(890)	(4,862)	(3,759)	(9,335)
Assets, Realized Gain (Loss)	(703)	2,581	98	2,533
Assets, Change In Net Unrealized Gain/(Loss)	2,844	(2,678)	3,261	(4,131)
Assets, Purchases	4,241	5,946	5,418	55,533
Assets, Sales	(10,198)	(42,572)	(22,589)	(111,135)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	28,403	56,803	28,403	56,803
Investments [Member] | Consumer loans and asset-backed securities backed by consumer loans [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	154,395	52,457	115,376	22,950
Assets, Accreted Discounts/Amortized Premiums	(2,919)	(1,413)	(8,515)	(4,832)
Assets, Realized Gain (Loss)	204	0	210	0
Assets, Change In Net Unrealized Gain/(Loss)	(2,290)	180	(2,839)	956
Assets, Purchases	51,775	43,830	140,731	84,969
Assets, Sales	(82,066)	(17,353)	(125,864)	(26,342)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	119,099	77,701	119,099	77,701
Investments [Member] | Corporate Debt [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	36,974	26,278	27,028	42,708
Assets, Accreted Discounts/Amortized Premiums	(52)	75	(99)	121
Assets, Realized Gain (Loss)	(1,942)	(28)	(1,687)	80
Assets, Change In Net Unrealized Gain/(Loss)	3,753	(3,212)	1,652	(5,601)
Assets, Purchases	83,700	9,609	136,020	22,239
Assets, Sales	(66,116)	(4,475)	(106,597)	(31,300)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	56,317	28,247	56,317	28,247
Investments [Member] | Real Estate Owned [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	4,162	9,502	12,522	8,635
Assets, Accreted Discounts/Amortized Premiums	0	0	0	0
Assets, Realized Gain (Loss)	53	437	2,291	685
Assets, Change In Net Unrealized Gain/(Loss)	(214)	(299)	(545)	228
Assets, Purchases	1,942	8,007	12,614	13,252
Assets, Sales	(2,359)	(2,817)	(23,298)	(7,970)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	3,584	14,830	3,584	14,830
Investments [Member] | Private Corporate Equity Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	19,418	22,349	22,088	14,512
Assets, Accreted Discounts/Amortized Premiums	0	0	0	0
Assets, Realized Gain (Loss)	733	0	704	116
Assets, Change In Net Unrealized Gain/(Loss)	349	(285)	(182)	213
Assets, Purchases	5,100	0	11,617	7,689
Assets, Sales	(10,082)	(58)	(18,709)	(524)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	15,518	22,006	15,518	22,006
Financial Derivatives - Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	6,992	9,796	6,567	11,487
Assets, Accreted Discounts/Amortized Premiums	0	0	0	0
Assets, Realized Gain (Loss)	3,826	497	4,137	(381)
Assets, Change In Net Unrealized Gain/(Loss)	(849)	(381)	(365)	568
Assets, Purchases	8,505	28	8,940	74
Assets, Sales	(4,835)	(737)	(5,640)	(2,545)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	13,639	9,203	13,639	9,203
Financial Derivatives - Assets [Member] | Credit Default Swaps On Asset Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	6,068	9,449	6,332	11,387
Assets, Accreted Discounts/Amortized Premiums	0	0	0	0
Assets, Realized Gain (Loss)	604	446	1,068	(717)
Assets, Change In Net Unrealized Gain/(Loss)	(221)	(310)	(476)	392
Assets, Purchases	65	10	77	35
Assets, Sales	(659)	(668)	(1,144)	(2,170)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	5,857	8,927	5,857	8,927
Financial Derivatives - Assets [Member] | Total Return Swaps [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	824	247	85	0
Assets, Accreted Discounts/Amortized Premiums	0	0	0	0
Assets, Realized Gain (Loss)	3,222	51	3,119	336
Assets, Change In Net Unrealized Gain/(Loss)	(628)	(71)	111	176
Assets, Purchases	954	18	1,377	39
Assets, Sales	(4,176)	(69)	(4,496)	(375)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	196	176	196	176
Financial Derivatives - Assets [Member] | Warrant [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	100	100	150	100
Assets, Accreted Discounts/Amortized Premiums	0	0	0	0
Assets, Realized Gain (Loss)	0	0	(50)	0
Assets, Change In Net Unrealized Gain/(Loss)	0	0	0	0
Assets, Purchases	7,486	0	7,486	0
Assets, Sales	0	0	0	0
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	7,586	100	7,586	100
Financial Derivatives - Liabilities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Liabilities, Begining Balance	(1,250)	(2,183)	(4,883)	(239)
Liabilities, Accreted Discounts/Amortized Premiums	0	0	0	0
Liabilities, Realized Gain/(Loss)	(2,125)	836	(6,569)	1,147
Liabilities, Change In Net Unrealized Gain/(Loss)	(274)	(1,134)	3,396	(3,077)
Liabilities, Purchases	1,937	(869)	6,623	(1,223)
Liabilities, Sales	227	33	(52)	75
Liabilities, Transfers into Level 3	0	0	0	0
Liabilities, Transfers out of Level 3	0	0	0	0
Liabilities, Ending Balance	(1,485)	(3,317)	(1,485)	(3,317)
Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Asset Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Liabilities, Begining Balance	(234)	(280)	(221)	(239)
Liabilities, Accreted Discounts/Amortized Premiums	0	0	0	0
Liabilities, Realized Gain/(Loss)	18	(18)	(61)	(60)
Liabilities, Change In Net Unrealized Gain/(Loss)	(67)	18	(42)	(23)
Liabilities, Purchases	47	0	47	0
Liabilities, Sales	(26)	18	15	60
Liabilities, Transfers into Level 3	0	0	0	0
Liabilities, Transfers out of Level 3	0	0	0	0
Liabilities, Ending Balance	(262)	(262)	(262)	(262)
Financial Derivatives - Liabilities [Member] | Total Return Swaps [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Liabilities, Begining Balance	(1,016)	(1,903)	(4,662)	0
Liabilities, Accreted Discounts/Amortized Premiums	0	0	0	0
Liabilities, Realized Gain/(Loss)	(2,143)	854	(6,508)	1,207
Liabilities, Change In Net Unrealized Gain/(Loss)	(207)	(1,152)	3,438	(3,054)
Liabilities, Purchases	1,890	(869)	6,576	(1,223)
Liabilities, Sales	253	15	(67)	15
Liabilities, Transfers into Level 3	0	0	0	0
Liabilities, Transfers out of Level 3	0	0	0	0
Liabilities, Ending Balance	(1,223)	$ (3,055)	(1,223)	$ (3,055)
Securities Sold Short - Securities Sold, Not Yet Purchased [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Liabilities, Begining Balance	(9,947)		(448)
Liabilities, Accreted Discounts/Amortized Premiums	0		(8)
Liabilities, Realized Gain/(Loss)	(122)		409
Liabilities, Change In Net Unrealized Gain/(Loss)	(7)		(566)
Liabilities, Purchases	20,974		32,230
Liabilities, Sales	(50,085)		(70,804)
Liabilities, Transfers into Level 3	0		0
Liabilities, Transfers out of Level 3	0		0
Liabilities, Ending Balance	(39,187)		(39,187)
Securities Sold Short - Securities Sold, Not Yet Purchased [Member] | Corporate Debt Sold Short [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Liabilities, Begining Balance	(9,947)		(448)
Liabilities, Accreted Discounts/Amortized Premiums	0		(8)
Liabilities, Realized Gain/(Loss)	(122)		409
Liabilities, Change In Net Unrealized Gain/(Loss)	(7)		(566)
Liabilities, Purchases	20,974		32,230
Liabilities, Sales	(50,085)		(70,804)
Liabilities, Transfers into Level 3	0		0
Liabilities, Transfers out of Level 3	0		0
Liabilities, Ending Balance	$ (39,187)		$ (39,187)