Consolidated Condensed Schedule Of Investments (Investments Sold Short) - USD ($) shares in Thousands, $ in Thousands		9 Months Ended		12 Months Ended
		Sep. 30, 2018		Dec. 31, 2017
Investments Sold, Not yet Purchased [Line Items]
Investments sold short, at fair value-		$ (695,349)		$ (642,240)
Proceeds from investments sold short		$ (697,686)		$ (640,202)
TBA - Fixed Rate Agency Securities Sold Short [Member]
Investments Sold, Not yet Purchased [Line Items]
Investment Sold, Not yet Purchased, Percent of Equity		(91.15%)	[1],[2],[3]	(74.11%)	[4],[5],[6]
Current Principal/Notional Amount		$ (559,037)		$ (442,197)
Investments sold short, at fair value-		(562,098)	[1],[3]	(460,189)	[4],[6]
Proceeds from investments sold short		(564,232)	[1],[3]	(459,953)	[4],[6]
TBA - Fixed Rate Agency Securities Sold Short [Member] | Government National Mortgage Association (30 Year) 3 Point 50 Percent [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount		$ (127,460)	[1],[3]	$ (24,410)	[4],[6]
Rate		3.50%	[1],[3]	3.50%	[4],[6]
Investments maturity date		2018-10	[1],[3]	2018-01	[4],[6]
Investments sold short, at fair value-		$ (126,713)	[1],[3]	$ (25,249)	[4],[6]
TBA - Fixed Rate Agency Securities Sold Short [Member] | Government National Mortgage Association (30 Year) 4 Point 00 Percent [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount		$ (92,883)	[1],[3]	$ (35,000)	[4],[6]
Rate		4.00%	[1],[3]	4.00%	[4],[6]
Investments maturity date		2018-10	[1],[3]	2018-02	[4],[6]
Investments sold short, at fair value-		$ (94,440)	[1],[3]	$ (36,485)	[4],[6]
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal Home Loan Mortgage Corporation (30 Year) 4 Point 00 Percent 201811 [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[1],[3]	$ (84,000)
Rate	[1],[3]	4.00%
Investments maturity date	[1],[3]	2018-11
Investments sold short, at fair value-	[1],[3]	$ (84,715)
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal National Mortgage Association (30 Year) 3 Point 50 Percent [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount		$ (76,912)	[1],[3]	$ (69,372)	[4],[6]
Rate		3.50%	[1],[3]	3.50%	[4],[6]
Investments maturity date		2018-10	[1],[3]	2018-01	[4],[6]
Investments sold short, at fair value-		$ (75,689)	[1],[3]	$ (71,247)	[4],[6]
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal National Mortgage Association (30 Year) 5 Point 00 Percent 201811 [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[1],[3]	$ (32,000)
Rate	[1],[3]	5.00%
Investments maturity date	[1],[3]	2018-11
Investments sold short, at fair value-	[1],[3]	$ (33,548)
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal National Mortgage Association (15 Year) 3 Point 50 Percent [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount		$ (28,320)	[1],[3]	$ (43,220)	[4],[6]
Rate		3.50%	[1],[3]	3.50%	[4],[6]
Investments maturity date		2018-10	[1],[3]	2018-01	[4],[6]
Investments sold short, at fair value-		$ (28,465)	[1],[3]	$ (44,618)	[4],[6]
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal Home Loan Mortgage Corporation (30 Year) 4.00% [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount		$ (25,797)	[1],[3]	$ (27,547)	[4],[6]
Rate		4.00%	[1],[3]	4.00%	[4],[6]
Investments maturity date		2018-10	[1],[3]	2018-01	[4],[6]
Investments sold short, at fair value-		$ (26,050)	[1],[3]	$ (28,815)	[4],[6]
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal National Mortgage Association (15 Year) 3 Point 00 Percent [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount		$ (25,490)	[1],[3]	$ (21,520)	[4],[6]
Rate		3.00%	[1],[3]	3.00%	[4],[6]
Investments maturity date		2018-10	[1],[3]	2018-01	[4],[6]
Investments sold short, at fair value-		$ (25,176)	[1],[3]	$ (21,923)	[4],[6]
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal Home Loan Mortgage Corporation (30 Year) 4 Point 50 Percent [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount		$ (23,631)	[1],[3]	$ (12,351)	[4],[6]
Rate		4.50%	[1],[3]	4.50%	[4],[6]
Investments maturity date		2018-10	[1],[3]	2018-01	[4],[6]
Investments sold short, at fair value-		$ (24,388)	[1],[3]	$ (13,134)	[4],[6]
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal National Mortgage Association (30 Year) 3 Point 00 Percent [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount		$ (17,457)	[1],[3]	$ (12,112)	[4],[6]
Rate		3.00%	[1],[3]	3.00%	[4],[6]
Investments maturity date		2018-10	[1],[3]	2018-01	[4],[6]
Investments sold short, at fair value-		$ (16,703)	[1],[3]	$ (12,113)	[4],[6]
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal National Mortgage Association (30 Year) 4 Point 50 Percent [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount		$ (13,610)	[1],[3]	$ (21,710)	[4],[6]
Rate		4.50%	[1],[3]	4.50%	[4],[6]
Investments maturity date		2018-10	[1],[3]	2018-01	[4],[6]
Investments sold short, at fair value-		$ (14,040)	[1],[3]	$ (23,097)	[4],[6]
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal National Mortgage Association (30 Year) 5 Point 50 Percent [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount		$ (6,860)	[1],[3]	$ (6,860)	[4],[6]
Rate		5.50%	[1],[3]	5.50%	[4],[6]
Investments maturity date		2018-10	[1],[3]	2018-01	[4],[6]
Investments sold short, at fair value-		$ (7,325)	[1],[3]	$ (7,520)	[4],[6]
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal National Mortgage Association (30 Year) 5 Point 00 Percent [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount		$ (4,617)	[1],[3]	$ (5,680)	[4],[6]
Rate		5.00%	[1],[3]	5.00%	[4],[6]
Investments maturity date		2018-10	[1],[3]	2018-01	[4],[6]
Investments sold short, at fair value-		$ (4,846)	[1],[3]	$ (6,104)	[4],[6]
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal Home Loan Mortgage Corporation (30 Year) 3 Point 00 Percent [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[4],[6]			$ (5,515)
Rate	[4],[6]			3.00%
Investments maturity date	[4],[6]			2018-01
Investments sold short, at fair value-	[4],[6]			$ (5,517)
TBA - Fixed Rate Agency Securities Sold Short [Member] | Government National Mortgage Association (30 Year) 3 Point 00 Percent [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[4],[6]			$ (1,800)
Rate	[4],[6]			3.00%
Investments maturity date	[4],[6]			2018-01
Investments sold short, at fair value-	[4],[6]			$ (1,813)
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal Home Loan Mortgage Corporation (15 Year) 3 Point 50 Percent [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[4],[6]			$ (1,100)
Rate	[4],[6]			3.50%
Investments maturity date	[4],[6]			2018-01
Investments sold short, at fair value-	[4],[6]			$ (1,137)
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal Home Loan Mortgage Corporation (30 Year) 4 Point 00 Percent 201802 [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[4],[6]			$ (68,000)
Rate	[4],[6]			4.00%
Investments maturity date	[4],[6]			2018-02
Investments sold short, at fair value-	[4],[6]			$ (71,028)
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal National Mortgage Association (30 Year) 4 Point 00 Percent [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[4],[6]			$ (55,000)
Rate	[4],[6]			4.00%
Investments maturity date	[4],[6]			2018-02
Investments sold short, at fair value-	[4],[6]			$ (57,447)
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal National Mortgage Association (30 Year) 4 Point 50 Percent 201802 [Member] | Mortgage-related Residential [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[4],[6]			$ (31,000)
Rate	[4],[6]			4.50%
Investments maturity date	[4],[6]			2018-02
Investments sold short, at fair value-	[4],[6]			$ (32,942)
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal National Mortgage Association [Member]
Investments Sold, Not yet Purchased [Line Items]
Investment Sold, Not yet Purchased, Percent of Equity		(33.37%)		(44.61%)
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal Home Loan Mortgage Corporation [Member]
Investments Sold, Not yet Purchased [Line Items]
Investment Sold, Not yet Purchased, Percent of Equity		(21.92%)		(19.27%)
TBA - Fixed Rate Agency Securities Sold Short [Member] | Government National Mortgage Association [Member]
Investments Sold, Not yet Purchased [Line Items]
Investment Sold, Not yet Purchased, Percent of Equity		(35.86%)		(10.23%)
US Government Debt Securities [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Investment Sold, Not yet Purchased, Percent of Equity		(8.56%)	[2],[3]	(8.54%)	[5],[6]
Investments sold short, at fair value-		$ (52,809)	[3]	$ (53,021)	[6]
Proceeds from investments sold short		(52,884)	[3]	(53,322)	[6]
US Government Debt Securities [Member] | U.S. Treasury Note, 2.88 Percent, Maturity Date 2023 09 [Member] | Government [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[3]	$ (36,380)
Rate	[3]	2.88%
Investments maturity date	[3]	2023-09
Investments sold short, at fair value-	[3]	$ (36,259)
US Government Debt Securities [Member] | U.S. Treasury Note, 2.88 Percent, Maturity Date 2028 08 [Member] | Government [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[3]	$ (9,414)
Rate	[3]	2.88%
Investments maturity date	[3]	2028-08
Investments sold short, at fair value-	[3]	$ (9,271)
US Government Debt Securities [Member] | U.S. Treasury Note, 2.75 Percent, Maturity Date 2023 05 [Member] | Government [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[3]	$ (2,300)
Rate	[3]	2.75%
Investments maturity date	[3]	2023-05
Investments sold short, at fair value-	[3]	$ (2,282)
US Government Debt Securities [Member] | U.S. Treasury Note, 2.75 Percent, Maturity Date 2023 04 [Member] | Government [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[3]	$ (1,355)
Rate	[3]	2.75%
Investments maturity date	[3]	2023-04
Investments sold short, at fair value-	[3]	$ (1,344)
US Government Debt Securities [Member] | U.S. Treasury Note, 2.88 Percent, Maturity Date 2028 05 [Member] | Government [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[3]	$ (1,004)
Rate	[3]	2.88%
Investments maturity date	[3]	2028-05
Investments sold short, at fair value-	[3]	$ (989)
US Government Debt Securities [Member] | U.S. Treasury Bond, 3.00 Percent, Maturity Date 2048 02 [Member] | Government [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[3]	$ (770)
Rate	[3]	3.00%
Investments maturity date	[3]	2048-02
Investments sold short, at fair value-	[3]	$ (742)
US Government Debt Securities [Member] | U.S. Treasury Note, 2.75 Percent, Maturity Date 2023 08 [Member] | Government [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[3]	$ (680)
Rate	[3]	2.75%
Investments maturity date	[3]	2023-08
Investments sold short, at fair value-	[3]	$ (674)
US Government Debt Securities [Member] | U.S. Treasury Note, 2.63 Percent, Maturity Date 2023 06 [Member] | Government [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[3]	$ (562)
Rate	[3]	2.63%
Investments maturity date	[3]	2023-06
Investments sold short, at fair value-	[3]	$ (554)
US Government Debt Securities [Member] | U.S. Treasury Note, 2.75 Percent, Maturity Date 2025 02 [Member] | Government [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[3]	$ (448)
Rate	[3]	2.75%
Investments maturity date	[3]	2025-02
Investments sold short, at fair value-	[3]	$ (442)
US Government Debt Securities [Member] | U.S. Treasury Bond, 2.75 Percent, Maturity Date 2047 08 [Member] | Government [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[3]	$ (275)
Rate	[3]	2.75%
Investments maturity date	[3]	2047-08
Investments sold short, at fair value-	[3]	$ (252)
US Government Debt Securities [Member] | U.S. Treasury Note, 2.25 Percent, Maturity Date 2027 02 [Member] | Government [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[6]			$ (30,501)
Rate	[6]			2.25%
Investments maturity date	[6]			2027-02
Investments sold short, at fair value-	[6]			$ (30,108)
US Government Debt Securities [Member] | US Treasury Note, 1.88 Percent, Maturity Date 2020 12 [Member] | Government [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[6]			$ (14,000)
Rate	[6]			1.88%
Investments maturity date	[6]			2020-12
Investments sold short, at fair value-	[6]			$ (13,961)
US Government Debt Securities [Member] | U.S. Treasury Note, 1.75 Percent, Maturity Date 2022 05 [Member] | Government [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[6]			$ (6,000)
Rate	[6]			1.75%
Investments maturity date	[6]			2022-05
Investments sold short, at fair value-	[6]			$ (5,896)
US Government Debt Securities [Member] | U.S. Treasury Note, 2.25 Percent, Maturity Date 2027 11 [Member] | Government [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[6]			$ (2,223)
Rate	[6]			2.25%
Investments maturity date	[6]			2027-11
Investments sold short, at fair value-	[6]			$ (2,192)
US Government Debt Securities [Member] | US Treasury Note, 2.00 Percent, Maturity Date 2022 11 [Member] | Government [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[6]			$ (615)
Rate	[6]			2.00%
Investments maturity date	[6]			2022-11
Investments sold short, at fair value-	[6]			$ (610)
US Government Debt Securities [Member] | U.S. Treasury Bond, 2.25 Percent, Maturity Date 2046 08 [Member] | Government [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[6]			$ (281)
Rate	[6]			2.25%
Investments maturity date	[6]			2046-08
Investments sold short, at fair value-	[6]			$ (254)
Debt Security, Government, Non-US [Member] | Europe [Member]
Investments Sold, Not yet Purchased [Line Items]
Investment Sold, Not yet Purchased, Percent of Equity		(3.18%)	[2],[3]	(5.98%)	[5],[6]
Investments sold short, at fair value-		$ (19,633)	[3]	$ (37,128)	[6]
Proceeds from investments sold short		(19,605)	[3]	(35,149)	[6]
Debt Security, Government, Non-US [Member] | European Sovereign Bond [Member] | Government [Member] | Europe [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[3]	(19,263)
Investments sold short, at fair value-	[3]	$ (19,633)
Debt Security, Government, Non-US [Member] | European Sovereign Bond [Member] | Government [Member] | Europe [Member] | Minimum [Member]
Investments Sold, Not yet Purchased [Line Items]
Rate	[3]	0.75%
Investments maturity date	[3]	2019-04
Debt Security, Government, Non-US [Member] | European Sovereign Bond [Member] | Government [Member] | Europe [Member] | Maximum [Member]
Investments Sold, Not yet Purchased [Line Items]
Rate	[3]	2.75%
Investments maturity date	[3]	2021-07
Debt Security, Government, Non-US [Member] | Spanish Sovereign Bond, 0.25 Percent [Member] | Government [Member] | Europe [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[6]			$ (16,516)
Rate	[6]			0.25%
Investments maturity date	[6]			2018-04
Investments sold short, at fair value-	[6]			$ (16,556)
Debt Security, Government, Non-US [Member] | Spanish Sovereign Bond, 0.75 Percent [Member] | Government [Member] | Europe [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[6]			$ (10,447)
Rate	[6]			0.75%
Investments maturity date	[6]			2021-07
Investments sold short, at fair value-	[6]			$ (10,704)
Debt Security, Government, Non-US [Member] | Spanish Sovereign Bond, 2.75 Percent [Member] | Government [Member] | Europe [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[6]			$ (9,474)
Rate	[6]			2.75%
Investments maturity date	[6]			2019-04
Investments sold short, at fair value-	[6]			$ (9,868)
Government debt [Member]
Investments Sold, Not yet Purchased [Line Items]
Investment Sold, Not yet Purchased, Percent of Equity		(11.74%)	[2],[3]	(14.52%)	[5],[6]
Investments sold short, at fair value-		$ (72,442)	[3]	$ (90,149)	[6]
Proceeds from investments sold short		$ (72,489)	[3]	$ (88,471)	[6]
Common Stock Sold Short [Member]
Investments Sold, Not yet Purchased [Line Items]
Investment Sold, Not yet Purchased, Percent of Equity		(3.80%)	[2],[3]	(5.91%)	[5],[6]
Investments sold short, at fair value-		$ (23,407)	[3]	$ (36,691)	[6]
Proceeds from investments sold short		(23,855)	[3]	(36,666)	[6]
Common Stock Sold Short [Member] | Exchange Traded Equity [Member] | Energy [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Investments sold short, at fair value-	[6]			$ (68)
Investment Sold, Not yet Purchased, Balance, Shares	[6]			(1)
Common Stock Sold Short [Member] | Exchange Traded Equity [Member] | Financial [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Investments sold short, at fair value-		$ (23,407)	[3]	$ (36,623)	[6]
Investment Sold, Not yet Purchased, Balance, Shares		(649)	[3]	(671)	[6]
Corporate Debt Sold Short [Member]
Investments Sold, Not yet Purchased [Line Items]
Investment Sold, Not yet Purchased, Percent of Equity		(6.07%)	[2],[3]	(8.89%)	[5],[6]
Investments sold short, at fair value-		$ (37,402)	[3]	$ (55,211)	[6]
Proceeds from investments sold short		(37,110)	[3]	(55,112)	[6]
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Basic Materials [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[3]	$ (2,080)
Rate	[3]	3.45%
Investments maturity date	[3]	2027-06
Investments sold short, at fair value-	[3]	$ (1,982)
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Communications [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount		(9,275)	[3]	(18,590)	[6]
Investments sold short, at fair value-		$ (9,327)	[3]	$ (17,196)	[6]
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Communications [Member] | North America [Member] | Minimum [Member]
Investments Sold, Not yet Purchased [Line Items]
Rate		3.40%	[3]	4.13%	[6]
Investments maturity date		2023-09	[3]	2022-07	[6]
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Communications [Member] | North America [Member] | Maximum [Member]
Investments Sold, Not yet Purchased [Line Items]
Rate		7.50%	[3]	10.50%	[6]
Investments maturity date		2027-03	[3]	2027-03	[6]
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Consumer [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount		$ (13,972)	[3]	$ (23,805)	[6]
Investments sold short, at fair value-		$ (14,041)	[3]	$ (23,854)	[6]
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Consumer [Member] | North America [Member] | Minimum [Member]
Investments Sold, Not yet Purchased [Line Items]
Rate		4.50%	[3]	2.88%	[6]
Investments maturity date		2020-10	[3]	2020-10	[6]
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Consumer [Member] | North America [Member] | Maximum [Member]
Investments Sold, Not yet Purchased [Line Items]
Rate		5.88%	[3]	6.75%	[6]
Investments maturity date		2024-11	[3]	2026-05	[6]
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Energy [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount		$ (3,810)	[3]	$ (13,311)	[6]
Investments sold short, at fair value-		$ (3,672)	[3]	$ (12,834)	[6]
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Energy [Member] | North America [Member] | Minimum [Member]
Investments Sold, Not yet Purchased [Line Items]
Rate		4.50%	[3]	3.25%	[6]
Investments maturity date		2022-04	[3]	2022-04	[6]
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Energy [Member] | North America [Member] | Maximum [Member]
Investments Sold, Not yet Purchased [Line Items]
Rate		8.25%	[3]	8.25%	[6]
Investments maturity date		2027-06	[3]	2027-06	[6]
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Financial [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount		$ (2,785)	[3]	$ (960)	[6]
Investments sold short, at fair value-		$ (2,854)	[3]	$ (1,019)	[6]
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Financial [Member] | North America [Member] | Minimum [Member]
Investments Sold, Not yet Purchased [Line Items]
Rate		3.75%	[3]	5.13%	[6]
Investments maturity date		2024-09	[3]	2022-03	[6]
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Financial [Member] | North America [Member] | Maximum [Member]
Investments Sold, Not yet Purchased [Line Items]
Rate		5.13%	[3]	5.25%	[6]
Investments maturity date		2027-06	[3]	2024-09	[6]
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Industrial Sector [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[3]	$ (3,670)
Investments sold short, at fair value-	[3]	$ (3,677)
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Industrial Sector [Member] | North America [Member] | Minimum [Member]
Investments Sold, Not yet Purchased [Line Items]
Rate	[3]	3.55%
Investments maturity date	[3]	2024-10
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Industrial Sector [Member] | North America [Member] | Maximum [Member]
Investments Sold, Not yet Purchased [Line Items]
Rate	[3]	5.90%
Investments maturity date	[3]	2027-02
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Technology Sector [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount		$ (905)	[3]	$ (330)	[6]
Rate		4.70%	[3]	3.63%	[6]
Investments maturity date		2023-04	[3]	2021-10	[6]
Investments sold short, at fair value-		$ (825)	[3]	$ (308)	[6]
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Utilities [Member] | North America [Member]
Investments Sold, Not yet Purchased [Line Items]
Current Principal/Notional Amount	[3]	$ (940)
Rate	[3]	7.25%
Investments maturity date	[3]	2026-05
Investments sold short, at fair value-	[3]	$ (1,024)
Investments Sold Short [Member]
Investments Sold, Not yet Purchased [Line Items]
Investment Sold, Not yet Purchased, Percent of Equity		(112.76%)	[2],[3]	(103.43%)	[5],[6]
Investments sold short, at fair value-		$ (695,349)	[3]	$ (642,240)	[6]
Proceeds from investments sold short		$ (697,686)	[3]	$ (640,202)	[6]

[1] At September 30, 2018, the Company's short investments guaranteed by the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation, and the Government National Mortgage Association, represented 33.37%, 21.92%, and 35.86% of Total Equity, respectively.

[2] Classification percentages are based on Total Equity.

[3] See Note 2 and Note 3 in Notes to Consolidated Financial Statements.

[4] At December 31, 2017, the Company's short investments guaranteed by the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation, and the Government National Mortgage Association, represented 44.61%, 19.27%, and 10.23% of Total Equity, respectively.

[5] Classification percentages are based on Total Equity.

[6] See Note 2 and Note 3 in Notes to Consolidated Financial Statements.