Commitments and Contingencies - Additional Information (Detail)			6 Months Ended
	Mar. 31, 2020 Officer	Oct. 17, 2019 Officer	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Contingencies And Commitments [Line Items]
Commitments related to performance bonds			$ 11,300,000	$ 9,300,000
Commitments related to performance bonds expiration month and year			2024-08
Letter of credit secured by pledge of collateral amount			$ 5,000,000.0
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
Restricted Cash
Contingencies And Commitments [Line Items]
Letter of credit secured by pledge of collateral amount			1,200,000
Long-term Investments [Member]
Contingencies And Commitments [Line Items]
Letter of credit secured by pledge of collateral amount			3,800,000
Minimum [Member]
Contingencies And Commitments [Line Items]
Collateral value required to be maintained			5,000,000.0
Maximum [Member]
Contingencies And Commitments [Line Items]
Collateral value required to be maintained			$ 12,000,000.0
Current Executive Officers [Member]
Contingencies And Commitments [Line Items]
Number of officers \| Officer	2	2
Former Executive Officers [Member]
Contingencies And Commitments [Line Items]
Number of officers \| Officer	1	1