Concentration of Credit Risk - Additional Information (Detail) - Credit Concentration Risk	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts Receivable
Concentration Risk [Line Items]
Concentration risk, percentage	100.00%	100.00%	100.00%
Revenue
Concentration Risk [Line Items]
Concentration risk, percentage	100.00%	100.00%	100.00%

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
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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