Investments - Additional Information (Detail) - USD ($)	3 Months Ended
Mar. 31, 2020	Dec. 31, 2019
Long-term GICs
Short-Term Investments [Line Items]
Commercial paper	$ 75,040,000	$ 0
Securities	$ 718,000	$ 0
Minimum \| Short-term GICs
Short-Term Investments [Line Items]
Investments interest rate	0.90%
Minimum \| Long-term GICs
Short-Term Investments [Line Items]
Investments interest rate	0.90%
Investments maturity term	12 months
Maximum \| Short-term GICs
Short-Term Investments [Line Items]
Investments interest rate	2.10%
Investments maturity term	12 months
Maximum \| Long-term GICs
Short-Term Investments [Line Items]
Investments interest rate	1.60%
Investments maturity term	24 months

Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(13)(2))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(19)(a)(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_CommercialPaper
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant