Significant Accounting Policies - Revenue by Major Customers (Detail) - Revenues - Customer Concentration Risk	3 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Private
Concentration Risk [Line Items]
Concentration risk percentage	39.40%	32.10%
Public
Concentration Risk [Line Items]
Concentration risk percentage	60.60%	67.90%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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