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Non-Marketable Investments - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Carrying value of the Company's non-marketable investments	$ 2,300,000		$ 2,800,000
Book value of investment			$ 400,000
Losses from non-marketable investments	200,000
Distributions received from funds	$ 400,000	$ 0
Limited Partnerships Investments [Member] | Minimum [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Ownership interest of Company	5.00%

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Carrying amount of investments in equity method investees and the carrying amount, after adjustment, of cost-method investments.

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Income received from cost and equity method investments funds during the period.

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Amount, after adjustment, of cost-method investment. Adjustments include, but are not limited to, dividends received in excess of earnings after date of investment that are considered a return of investment and other than temporary impairments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Name Accounting Standards Codification
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-Section 50
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-Name Accounting Standards Codification
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The net realized gains or losses on investments during the period, not including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

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Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).

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-Publisher FASB
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