Financial Instruments - Company's Investments in Hedge Funds and Private Equity Funds Measured at Fair Value Based on Net Asset Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 66,602	$ 104,888
Unfunded Commitment	212	2,586
Hedge Funds, Fixed Income/Credit-Related [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Fair Value	38,972	57,532
Unfunded Commitment	0	0
Hedge Funds, Multi-Strategy [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Fair Value	18,930	37,890
Unfunded Commitment	0	0
Private Equity Funds [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Fair Value	8,700	9,466
Unfunded Commitment	$ 212	$ 2,586

Fair value of investments in certain entities that calculate net asset value per share, including, but not limited to, by unit, membership interest, or other ownership interest. Investments include, but are not limited to, investments in certain hedge funds, venture capital funds, private equity funds, real estate partnerships or funds.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=SL6742756-110258

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=SL6742756-110258

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- Details

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