Business acquisition equity interest issued or issuable for each share of acquired entity.

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- Definition

Commitments related to performance bonds.

+ References

No definition available.

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- Definition

Commitments related to performance bonds expiration month and year.

+ References

No definition available.

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- Definition

Amount of contributions made that have been applied to private equity fund commitments.

+ References

No definition available.

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- Definition

Contingencies and commitments.

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No definition available.

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- Definition

Investments in and Advances in Affiliates, at Fair Value Percentage

+ References

No definition available.

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- Definition

Letter of credit secured by pledge of a portion of fixed income securities.

+ References

No definition available.

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- Definition

Number of officers.

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No definition available.

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- Definition

Date when the business acquisition agreement was executed, in CCYY-MM-DD format.

+ References

No definition available.

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- Definition

Percentage of voting equity interests acquired at the acquisition date in the business combination.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
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- Definition

Amount of assets pledged to secure a debt instrument.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
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- Definition

Cost of the investment.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-SubTopic 210
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- Definition

Number of shares of affiliates held for management investment companies.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 946
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Commitments and Contingencies - Additional Information (Detail)			9 Months Ended
	Aug. 30, 2021 shares	Mar. 31, 2020 Officer	Sep. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Contingencies And Commitments [Line Items]
Commitments related to performance bonds			$ 20,900,000		$ 15,200,000
Commitments related to performance bonds expiration month and year			2024-08
Letter of credit secured by pledge of a portion of fixed income securities			$ 18,400,000
Commitments towards private equity funds			4,900,000
Investment Commitments [Member]
Contingencies And Commitments [Line Items]
Aggregate investment committed in private equity funds			5,000,000.0
Long-term Investments [Member]
Contingencies And Commitments [Line Items]
Letter of credit secured by pledge of a portion of fixed income securities			18,300,000
Minimum [Member]
Contingencies And Commitments [Line Items]
Collateral value required to be maintained				$ 15,000,000.0
Maximum [Member] \| Restricted Cash [Member]
Contingencies And Commitments [Line Items]
Letter of credit secured by pledge of a portion of fixed income securities			$ 100,000
Acorn HoldCo, Inc., [Member]
Contingencies And Commitments [Line Items]
Business combination date of agreement	Aug. 30, 2021
Acorn HoldCo, Inc., [Member] \| ADTRAN INC [Member]
Contingencies And Commitments [Line Items]
Percentage of ownership interest acquired	54.00%
Acorn HoldCo, Inc., [Member] \| ADTRAN INC [Member] \| Common Stock [Member]
Contingencies And Commitments [Line Items]
Number of shares issuable for each share of acquired entity \| shares	1
Acorn HoldCo, Inc., [Member] \| ADVA Optical Networking SE, [Member]
Contingencies And Commitments [Line Items]
Percentage of ownership interest acquired	46.00%
Acorn HoldCo, Inc., [Member] \| ADVA Optical Networking SE, [Member] \| Common Stock [Member]
Contingencies And Commitments [Line Items]
Number of shares issuable for each share of acquired entity \| shares	0.8244
Acorn HoldCo, Inc., [Member] \| EGORA Holding GmbH and Egora Investments GmbH [Member] \| Irrevocable Undertaking [Member]
Contingencies And Commitments [Line Items]
Number of shares issuable \| shares	7,000,000
Percentage of ownership interest acquired	13.70%
Current Executive Officers [Member]
Contingencies And Commitments [Line Items]
Number of officers \| Officer		2
Former Executive Officers [Member]
Contingencies And Commitments [Line Items]
Number of officers \| Officer		1