Valuation (Fair Value Measurement Using Significant Unobservable Inputs) (Details) - Level 3 [Member] - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2017		Sep. 30, 2016	Sep. 30, 2017		Sep. 30, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	$ 537,345		$ 519,124	$ 523,837		$ 493,541
Assets, Accreted Discounts/Amortized Premiums	(4,033)		(4,129)	(19,509)		(12,918)
Assets, Realized Gain (Loss)	2,218		1,217	5,235		5,730
Assets, Change In Net Unrealized Gain/(Loss)	(2,769)		8,012	14,056		(1,860)
Assets, Purchases	94,748		199,211	438,608		420,365
Assets, Sales	(72,962)		(234,819)	(355,023)		(418,307)
Assets, Transfers into Level 3	7,692		1,517	15,043		8,360
Assets, Transfers out of Level 3	(16,497)		(13,815)	(76,505)		(18,593)
Assets, Ending Balance	545,742		476,318	545,742		476,318
Liabilities, Begining Balance			(11,509)			(6,159)
Liabilities, Accreted Discounts/Amortized Premiums			0			(8)
Liabilities, Realized Gain/(Loss)			(2,247)			(6,160)
Liabilities, Change In Net Unrealized Gain/(Loss)			(119)			3,508
Liabilities Purchases/Payments			22,911			38,853
Liabilities, Sales/Issuance			(49,858)			(70,856)
Liabilities, Transfers into Level 3			0			0
Liabilities, Transfers out of Level 3			0			0
Liabilities, Ending Balance			(40,822)			(40,822)
Guarantees [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Liabilities, Begining Balance			(312)			(828)
Liabilities, Accreted Discounts/Amortized Premiums			0			0
Liabilities, Realized Gain/(Loss)			0			0
Liabilities, Change In Net Unrealized Gain/(Loss)			162			678
Liabilities, Payments			0			0
Liabilities, Issuances			0			0
Liabilities, Transfers into Level 3			0			0
Liabilities, Transfers out of Level 3			0			0
Liabilities, Ending Balance			(150)			(150)
Unrealized Gain Loss On Guarantees Level 3 Held At End Of Period			200			700
Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	532,238		512,132	518,250		486,974
Assets, Accreted Discounts/Amortized Premiums	(4,033)		(4,129)	(19,509)		(12,918)
Assets, Realized Gain (Loss)	1,594		(2,609)	4,121		1,593
Assets, Change In Net Unrealized Gain/(Loss)	(2,192)		8,861	15,013		(1,495)
Assets, Purchases	94,721		190,706	438,513		411,425
Assets, Sales	(72,311)		(229,984)	(353,714)		(412,667)
Assets, Transfers into Level 3	7,692		1,517	15,043		8,360
Assets, Transfers out of Level 3	(16,497)		(13,815)	(76,505)		(18,593)
Assets, Ending Balance	541,212		462,679	541,212		462,679
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(2,900)		600	2,800		(10,400)
Investments [Member] | Agency residential mortgage-backed securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	4,896		20,506	29,622		24,918
Assets, Accreted Discounts/Amortized Premiums	(377)		(1,821)	(7,233)		(5,766)
Assets, Realized Gain (Loss)	(78)		(77)	(515)		(168)
Assets, Change In Net Unrealized Gain/(Loss)	0		(169)	(140)		(849)
Assets, Purchases	1,649		1,385	3,962		1,689
Assets, Sales	(28)		0	(153)		0
Assets, Transfers into Level 3	772		0	0		0
Assets, Transfers out of Level 3	(1,015)		0	(19,724)		0
Assets, Ending Balance	5,819		19,824	5,819		19,824
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	79,123		112,511	90,083		116,435
Assets, Accreted Discounts/Amortized Premiums	261		256	1,672		1,518
Assets, Realized Gain (Loss)	1,018		(958)	1,334		(1,305)
Assets, Change In Net Unrealized Gain/(Loss)	409		6,086	7,319		2,995
Assets, Purchases	3,040		0	31,117		7,439
Assets, Sales	(9,116)		(23,652)	(37,278)		(34,904)
Assets, Transfers into Level 3	5,207		1,517	15,043		8,360
Assets, Transfers out of Level 3	(6,294)		(13,815)	(35,642)		(18,593)
Assets, Ending Balance	73,648		81,945	73,648		81,945
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	13,809		34,942	43,268		34,145
Assets, Accreted Discounts/Amortized Premiums	(144)		429	574		1,315
Assets, Realized Gain (Loss)	(752)		87	(3,434)		409
Assets, Change In Net Unrealized Gain/(Loss)	934		(292)	7,873		(4,132)
Assets, Purchases	2,100		5,335	2,120		13,179
Assets, Sales	(5,718)		(3,556)	(31,542)		(7,971)
Assets, Transfers into Level 3	1,713		0	0		0
Assets, Transfers out of Level 3	(310)		0	(7,227)		0
Assets, Ending Balance	11,632		36,945	11,632		36,945
Investments [Member] | Commercial Mortgage Loans [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	65,896		49,466	61,129		66,399
Assets, Accreted Discounts/Amortized Premiums	140		801	771		2,073
Assets, Realized Gain (Loss)	0		72	416		254
Assets, Change In Net Unrealized Gain/(Loss)	17		(1,140)	1,167		(917)
Assets, Purchases	4,342		13,226	31,887		26,650
Assets, Sales	(2,500)		(5,456)	(27,475)		(37,490)
Assets, Transfers into Level 3	0		0	0		0
Assets, Transfers out of Level 3	0		0	0		0
Assets, Ending Balance	67,895		56,969	67,895		56,969
Investments [Member] | Residential Mortgage Loans [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	136,097		46,649	84,290		22,089
Assets, Accreted Discounts/Amortized Premiums	(874)		67	(196)		315
Assets, Realized Gain (Loss)	388		(78)	1,469		787
Assets, Change In Net Unrealized Gain/(Loss)	(1,013)		(66)	(1,090)		61
Assets, Purchases	37,170		24,002	108,356		56,068
Assets, Sales	(8,805)		(26,499)	(29,866)		(35,245)
Assets, Transfers into Level 3	0		0	0		0
Assets, Transfers out of Level 3	0		0	0		0
Assets, Ending Balance	162,963		44,075	162,963		44,075
Investments [Member] | Collateralized Loan Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	42,536		33,109	44,956		45,974
Assets, Accreted Discounts/Amortized Premiums	346		(890)	(5,702)		(3,759)
Assets, Realized Gain (Loss)	61		(703)	1,477		98
Assets, Change In Net Unrealized Gain/(Loss)	(839)		2,844	2,135		3,261
Assets, Purchases	7,108		4,241	52,269		5,418
Assets, Sales	(13,416)		(10,198)	(54,305)		(22,589)
Assets, Transfers into Level 3	0		0	0		0
Assets, Transfers out of Level 3	(8,878)		0	(13,912)		0
Assets, Ending Balance	26,918		28,403	26,918		28,403
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	108,671		154,395	107,157	[1]	115,376
Assets, Accreted Discounts/Amortized Premiums	(3,366)		(2,919)	(9,631)	[1]	(8,515)
Assets, Realized Gain (Loss)	500		204	426	[1]	210
Assets, Change In Net Unrealized Gain/(Loss)	(528)		(2,290)	(247)	[1]	(2,839)
Assets, Purchases	33,125		51,775	83,138	[1]	140,731
Assets, Sales	(22,062)		(82,066)	(64,503)	[1]	(125,864)
Assets, Transfers into Level 3	0		0	0	[1]	0
Assets, Transfers out of Level 3	0		0	0	[1]	0
Assets, Ending Balance	116,340	[1]	119,099	116,340	[1]	119,099
Investments [Member] | Corporate Debt [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	20,535		36,974	25,004		27,028
Assets, Accreted Discounts/Amortized Premiums	(19)		(52)	236		(99)
Assets, Realized Gain (Loss)	128		(1,942)	676		(1,687)
Assets, Change In Net Unrealized Gain/(Loss)	(415)		3,753	(229)		1,652
Assets, Purchases	409		83,700	83,900		136,020
Assets, Sales	(7,730)		(66,116)	(96,679)		(106,597)
Assets, Transfers into Level 3	0		0	0		0
Assets, Transfers out of Level 3	0		0	0		0
Assets, Ending Balance	12,908		56,317	12,908		56,317
Investments [Member] | Real Estate Owned [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	24,977		4,162	3,349		12,522
Assets, Accreted Discounts/Amortized Premiums	0		0	0		0
Assets, Realized Gain (Loss)	0		53	424		2,291
Assets, Change In Net Unrealized Gain/(Loss)	49		(214)	(246)		(545)
Assets, Purchases	1,137		1,942	25,348		12,614
Assets, Sales	(401)		(2,359)	(3,113)		(23,298)
Assets, Transfers into Level 3	0		0	0		0
Assets, Transfers out of Level 3	0		0	0		0
Assets, Ending Balance	25,762		3,584	25,762		3,584
Investments [Member] | Corporate Equity Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	35,698		19,418	29,392	[1]	22,088
Assets, Accreted Discounts/Amortized Premiums	0		0	0	[1]	0
Assets, Realized Gain (Loss)	329		733	1,848	[1]	704
Assets, Change In Net Unrealized Gain/(Loss)	(806)		349	(1,529)	[1]	(182)
Assets, Purchases	4,641		5,100	16,416	[1]	11,617
Assets, Sales	(2,535)		(10,082)	(8,800)	[1]	(18,709)
Assets, Transfers into Level 3	0		0	0	[1]	0
Assets, Transfers out of Level 3	0		0	0	[1]	0
Assets, Ending Balance	37,327	[1]	15,518	37,327	[1]	15,518
Investments 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)
Unrealized Gain (Loss) On Investments Sold Short, Level 3, Held At End Of Period			(30)			(300)
Investments Sold Short [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)
Financial Derivatives - Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	5,107		6,992	5,587		6,567
Assets, Accreted Discounts/Amortized Premiums	0		0	0		0
Assets, Realized Gain (Loss)	624		3,826	1,114		4,137
Assets, Change In Net Unrealized Gain/(Loss)	(577)		(849)	(957)		(365)
Assets, Purchases	27		8,505	95		8,940
Assets, Sales	(651)		(4,835)	(1,309)		(5,640)
Assets, Transfers into Level 3	0		0	0		0
Assets, Transfers out of Level 3	0		0	0		0
Assets, Ending Balance	4,530		13,639	4,530		13,639
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(600)		400	(800)		(300)
Financial Derivatives - Assets [Member] | Total Return Swaps [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	0		824	155		85
Assets, Accreted Discounts/Amortized Premiums	0		0	0		0
Assets, Realized Gain (Loss)	21		3,222	243		3,119
Assets, Change In Net Unrealized Gain/(Loss)	0		(628)	(155)		111
Assets, Purchases	0		954	0		1,377
Assets, Sales	(21)		(4,176)	(243)		(4,496)
Assets, Transfers into Level 3	0		0	0		0
Assets, Transfers out of Level 3	0		0	0		0
Assets, Ending Balance	0		196	0		196
Financial Derivatives - Assets [Member] | Warrant [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance			100	106		150
Assets, Accreted Discounts/Amortized Premiums			0	0		0
Assets, Realized Gain (Loss)			0	(100)		(50)
Assets, Change In Net Unrealized Gain/(Loss)			0	(6)		0
Assets, Purchases			7,486	0		7,486
Assets, Sales			0	0		0
Assets, Transfers into Level 3			0	0		0
Assets, Transfers out of Level 3			0	0		0
Assets, Ending Balance	0		7,586	0		7,586
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	5,107		6,068	5,326		6,332
Assets, Accreted Discounts/Amortized Premiums	0		0	0		0
Assets, Realized Gain (Loss)	603		604	971		1,068
Assets, Change In Net Unrealized Gain/(Loss)	(577)		(221)	(796)		(476)
Assets, Purchases	27		65	95		77
Assets, Sales	(630)		(659)	(1,066)		(1,144)
Assets, Transfers into Level 3	0		0	0		0
Assets, Transfers out of Level 3	0		0	0		0
Assets, Ending Balance	4,530		5,857	4,530		5,857
Financial Derivatives - Liabilities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Liabilities, Begining Balance	(207)		(1,250)	(505)		(4,883)
Liabilities, Accreted Discounts/Amortized Premiums	0		0	0		0
Liabilities, Realized Gain/(Loss)	(7)		(2,125)	(764)		(6,569)
Liabilities, Change In Net Unrealized Gain/(Loss)	0		(274)	726		3,396
Liabilities, Purchases	7		1,937	776		6,623
Liabilities, Sales	0		227	(440)		(52)
Liabilities, Transfers into Level 3	0		0	0		0
Liabilities, Transfers out of Level 3	0		0	0		0
Liabilities, Ending Balance	(207)		(1,485)	(207)		(1,485)
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)			(1,100)	50		(1,200)
Financial Derivatives - Liabilities [Member] | Total Return Swaps [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Liabilities, Begining Balance	0		(1,016)	(249)		(4,662)
Liabilities, Accreted Discounts/Amortized Premiums	0		0	0		0
Liabilities, Realized Gain/(Loss)	13		(2,143)	(279)		(6,508)
Liabilities, Change In Net Unrealized Gain/(Loss)	0		(207)	249		3,438
Liabilities, Purchases	(13)		1,890	291		6,576
Liabilities, Sales	0		253	(12)		(67)
Liabilities, Transfers into Level 3	0		0	0		0
Liabilities, Transfers out of Level 3	0		0	0		0
Liabilities, Ending Balance	0		(1,223)	0		(1,223)
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	(207)		(234)	(256)		(221)
Liabilities, Accreted Discounts/Amortized Premiums	0		0	0		0
Liabilities, Realized Gain/(Loss)	(20)		18	(485)		(61)
Liabilities, Change In Net Unrealized Gain/(Loss)	0		(67)	477		(42)
Liabilities, Purchases	20		47	485		47
Liabilities, Sales	0		(26)	(428)		15
Liabilities, Transfers into Level 3	0		0	0		0
Liabilities, Transfers out of Level 3	0		0	0		0
Liabilities, Ending Balance	$ (207)		$ (262)	$ (207)		$ (262)

[1] Conformed to current period presentation.