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Summary of Impact of Derivative Financial Instruments to Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Net Investment Hedges | Foreign Currency Contracts
Derivative [Line Items]
Realized Gains (Losses)	$ 0		$ 0	$ (8)
Freestanding Derivatives
Derivative [Line Items]
Realized Gains (Losses)	(1,460)	$ 12,836	(1,054)	9,974
Net Change in Unrealized Gain (Loss)	(905)	39,327	(5,863)	(1,771)
Freestanding Derivatives | Total Return Swaps
Derivative [Line Items]
Realized Gains (Losses)	(275)	173	(395)	174
Net Change in Unrealized Gain (Loss)	393	(5)	1,371	52
Freestanding Derivatives | Credit Default Swap
Derivative [Line Items]
Realized Gains (Losses)	881	(107)	1,991	(508)
Net Change in Unrealized Gain (Loss)	(294)	615	3,647	488
Freestanding Derivatives | Interest Rate Contracts
Derivative [Line Items]
Realized Gains (Losses)	(416)	449	(2,664)	2,070
Net Change in Unrealized Gain (Loss)	(2,892)	37,261	(11,155)	(39)
Freestanding Derivatives | Foreign Currency Contracts
Derivative [Line Items]
Realized Gains (Losses)	(1,526)	12,321	146	8,238
Net Change in Unrealized Gain (Loss)	1,773	$ 1,456	209	$ (2,272)
Freestanding Derivatives | Equity Options
Derivative [Line Items]
Realized Gains (Losses)	(124)		(132)
Net Change in Unrealized Gain (Loss)	$ 115		$ 65

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- Definition

The difference between the book value and the sale price of options, swaps, futures, forward contracts, and other derivative instruments. This element refers to the gain (loss) included in earnings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13(h))
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

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The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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