v3.10.0.1
Consolidated Condensed Schedule Of Investments (Investments Sold Short) - USD ($)
shares in Thousands, $ in Thousands
 6 Months Ended 12 Months Ended
Jun. 30, 2018
Dec. 31, 2017
Investments Sold, Not yet Purchased [Line Items]    
Investments sold short, at fair value- $ (882,146) $ (642,240)
Proceeds from investments sold short $ (880,825) $ (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 (100.88%) [1],[2],[3] (74.11%) [4],[5],[6]
Current Principal/Notional Amount $ (608,800) $ (442,197)
Investments sold short, at fair value- (618,665) [1],[3] (460,189) [4],[6]
Proceeds from investments sold short (616,872) [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 $ (134,610) [1],[3] $ (24,410) [4],[6]
Rate 3.50% [1],[3] 3.50% [4],[6]
Investments maturity date 2018-07 [1],[3] 2018-01 [4],[6]
Investments sold short, at fair value- $ (135,083) [1],[3] $ (25,249) [4],[6]
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal Home Loan Mortgage Corporation (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 [1],[3] $ (92,000)  
Rate [1],[3] 4.00%  
Investments maturity date [1],[3] 2018-08  
Investments sold short, at fair value- [1],[3] $ (93,642)  
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 $ (82,133) [1],[3] $ (35,000) [4],[6]
Rate 4.00% [1],[3] 4.00% [4],[6]
Investments maturity date 2018-07 [1],[3] 2018-02 [4],[6]
Investments sold short, at fair value- $ (84,167) [1],[3] $ (36,485) [4],[6]
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal National Mortgage Association (30 Year) 3.50% [Member] | Mortgage-related Residential [Member] | North America [Member]    
Investments Sold, Not yet Purchased [Line Items]    
Current Principal/Notional Amount [1],[3] $ (63,000)  
Rate [1],[3] 3.50%  
Investments maturity date [1],[3] 2018-08  
Investments sold short, at fair value- [1],[3] $ (62,626)  
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 $ (48,930) [1],[3] $ (5,680) [4],[6]
Rate 5.00% [1],[3] 5.00% [4],[6]
Investments maturity date 2018-07 [1],[3] 2018-01 [4],[6]
Investments sold short, at fair value- $ (51,839) [1],[3] $ (6,104) [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 $ (42,801) [1],[3] $ (12,351) [4],[6]
Rate 4.50% [1],[3] 4.50% [4],[6]
Investments maturity date 2018-08 [1],[3] 2018-01 [4],[6]
Investments sold short, at fair value- $ (44,475) [1],[3] $ (13,134) [4],[6]
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 $ (38,520) [1],[3] $ (43,220) [4],[6]
Rate 3.50% [1],[3] 3.50% [4],[6]
Investments maturity date 2018-07 [1],[3] 2018-01 [4],[6]
Investments sold short, at fair value- $ (38,976) [1],[3] $ (44,618) [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 2018-07 [1],[3] 2018-01 [4],[6]
Investments sold short, at fair value- $ (25,339) [1],[3] $ (21,923) [4],[6]
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 $ (20,402) [1],[3] $ (69,372) [4],[6]
Rate 3.50% [1],[3] 3.50% [4],[6]
Investments maturity date 2018-07 [1],[3] 2018-01 [4],[6]
Investments sold short, at fair value- $ (20,305) [1],[3] $ (71,247) [4],[6]
TBA - Fixed Rate Agency Securities Sold Short [Member] | Federal National Mortgage Association (30 Year) 5 Point 00 Percent 201808 [Member] | Mortgage-related Residential [Member] | North America [Member]    
Investments Sold, Not yet Purchased [Line Items]    
Current Principal/Notional Amount [1],[3] $ (13,970)  
Rate [1],[3] 5.00%  
Investments maturity date [1],[3] 2018-08  
Investments sold short, at fair value- [1],[3] $ (14,773)  
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 $ (13,112) [1],[3] $ (12,112) [4],[6]
Rate 3.00% [1],[3] 3.00% [4],[6]
Investments maturity date 2018-08 [1],[3] 2018-01 [4],[6]
Investments sold short, at fair value- $ (12,687) [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 $ (11,110) [1],[3] $ (21,710) [4],[6]
Rate 4.50% [1],[3] 4.50% [4],[6]
Investments maturity date 2018-07 [1],[3] 2018-01 [4],[6]
Investments sold short, at fair value- $ (11,569) [1],[3] $ (23,097) [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 $ (9,297) [1],[3] $ (27,547) [4],[6]
Rate 4.00% [1],[3] 4.00% [4],[6]
Investments maturity date 2018-07 [1],[3] 2018-01 [4],[6]
Investments sold short, at fair value- $ (9,477) [1],[3] $ (28,815) [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 2018-08 [1],[3] 2018-01 [4],[6]
Investments sold short, at fair value- $ (7,348) [1],[3] $ (7,520) [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 $ (5,515) [1],[3] $ (5,515) [4],[6]
Rate 3.00% [1],[3] 3.00% [4],[6]
Investments maturity date 2018-08 [1],[3] 2018-01 [4],[6]
Investments sold short, at fair value- $ (5,332) [1],[3] $ (5,517) [4],[6]
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 $ (1,050) [1],[3] $ (1,800) [4],[6]
Rate 3.00% [1],[3] 3.00% [4],[6]
Investments maturity date 2018-07 [1],[3] 2018-01 [4],[6]
Investments sold short, at fair value- $ (1,027) [1],[3] $ (1,813) [4],[6]
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 (40.02%) (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 (24.94%) (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 (35.92%) (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 (25.96%) [2],[3] (8.54%) [5],[6]
Investments sold short, at fair value- $ (159,220) [3] $ (53,021) [6]
Proceeds from investments sold short (159,005) [3] (53,322) [6]
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] $ (111,830)  
Rate [3] 2.75%  
Investments maturity date [3] 2023-05  
Investments sold short, at fair value- [3] $ (111,975)  
US Government Debt Securities [Member] | U.S. Treasury Note, 2.63 Percent, Maturity Date 2021 06 [Member] | Government [Member] | North America [Member]    
Investments Sold, Not yet Purchased [Line Items]    
Current Principal/Notional Amount [3] $ (15,300)  
Rate [3] 2.63%  
Investments maturity date [3] 2021-06  
Investments sold short, at fair value- [3] $ (15,303)  
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] $ (13,321)  
Rate [3] 2.88%  
Investments maturity date [3] 2028-05  
Investments sold short, at fair value- [3] $ (13,349)  
US Government Debt Securities [Member] | U.S. Treasury Note, 2.88 Percent, Maturity Date 2025 05 [Member] | Government [Member] | North America [Member]    
Investments Sold, Not yet Purchased [Line Items]    
Current Principal/Notional Amount [3] $ (10,200)  
Rate [3] 2.88%  
Investments maturity date [3] 2025-05  
Investments sold short, at fair value- [3] $ (10,242)  
US Government Debt Securities [Member] | U.S. Treasury Note, 2.75 Percent, Maturity Date 2028 02 [Member] | Government [Member] | North America [Member]    
Investments Sold, Not yet Purchased [Line Items]    
Current Principal/Notional Amount [3] $ (3,094)  
Rate [3] 2.75%  
Investments maturity date [3] 2028-02  
Investments sold short, at fair value- [3] $ (3,067)  
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] $ (2,561)  
Rate [3] 2.75%  
Investments maturity date [3] 2023-04  
Investments sold short, at fair value- [3] $ (2,563)  
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] $ (1,050)  
Rate [3] 3.00%  
Investments maturity date [3] 2048-02  
Investments sold short, at fair value- [3] $ (1,053)  
US Government Debt Securities [Member] | U.S. Treasury Note, 1.88 Percent, Maturity Date 2019 12 [Member] | Government [Member] | North America [Member]    
Investments Sold, Not yet Purchased [Line Items]    
Current Principal/Notional Amount [3] $ (968)  
Rate [3] 1.88%  
Investments maturity date [3] 2019-12  
Investments sold short, at fair value- [3] $ (960)  
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] $ (446)  
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] $ (262)  
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)
Foreign Government Debt Securities [Member] | Europe [Member]    
Investments Sold, Not yet Purchased [Line Items]    
Investment Sold, Not yet Purchased, Percent of Equity (3.24%) [2],[3] (5.98%) [5],[6]
Investments sold short, at fair value- $ (19,866) [3] $ (37,128) [6]
Proceeds from investments sold short (19,668) [3] (35,149) [6]
Foreign Government Debt Securities [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)
Foreign Government Debt Securities [Member] | European Sovereign Bond [Member] | Government [Member] | Europe [Member]    
Investments Sold, Not yet Purchased [Line Items]    
Current Principal/Notional Amount [3] (19,370)  
Investments sold short, at fair value- [3] $ (19,866)  
Foreign Government Debt Securities [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  
Foreign Government Debt Securities [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  
Foreign Government Debt Securities [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)
Foreign Government Debt Securities [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 (29.20%) [2],[3] (14.52%) [5],[6]
Investments sold short, at fair value- $ (179,086) [3] $ (90,149) [6]
Proceeds from investments sold short $ (178,673) [3] $ (88,471) [6]
Common Stock Sold Short [Member]    
Investments Sold, Not yet Purchased [Line Items]    
Investment Sold, Not yet Purchased, Percent of Equity (5.49%) [2],[3] (5.91%) [5],[6]
Investments sold short, at fair value- $ (33,684) [3] $ (36,691) [6]
Proceeds from investments sold short (34,786) [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- $ (33,684) [3] $ (36,623) [6]
Investment Sold, Not yet Purchased, Balance, Shares (774) [3] (671) [6]
Corporate Debt Sold Short [Member]    
Investments Sold, Not yet Purchased [Line Items]    
Investment Sold, Not yet Purchased, Percent of Equity (8.27%) [2],[3] (8.89%) [5],[6]
Investments sold short, at fair value- $ (50,711) [3] $ (55,211) [6]
Proceeds from investments sold short (50,494) [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] $ (2,695)  
Rate [3] 3.45%  
Investments maturity date [3] 2027-06  
Investments sold short, at fair value- [3] $ (2,551)  
Corporate Debt Sold Short [Member] | Various Issuer [Member] | Communications [Member] | North America [Member]    
Investments Sold, Not yet Purchased [Line Items]    
Current Principal/Notional Amount (15,485) [3] (18,590) [6]
Investments sold short, at fair value- $ (14,359) [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 2022-09 [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 10.50% [3] 10.50% [6]
Investments maturity date 2025-05 [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 $ (15,467) [3] $ (23,805) [6]
Investments sold short, at fair value- $ (15,396) [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 4.35% [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 2028-02 [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 $ (9,125) [3] $ (13,311) [6]
Investments sold short, at fair value- $ (8,882) [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 $ (2,345) [3] $ (960) [6]
Investments sold short, at fair value- $ (2,381) [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 2026-03 [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] $ (5,955)  
Investments sold short, at fair value- [3] $ (5,908)  
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 $ (255) [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- $ (230) [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] $ (1,004)  
Investments Sold Short [Member]    
Investments Sold, Not yet Purchased [Line Items]    
Investment Sold, Not yet Purchased, Percent of Equity (143.84%) [2],[3] (103.43%) [5],[6]
Investments sold short, at fair value- $ (882,146) [3] $ (642,240) [6]
Proceeds from investments sold short $ (880,825) [3] $ (640,202) [6]
[1] At June 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 40.02%, 24.94%, and 35.92% 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.