Trade Accounts Receivable and Allowance for Doubtful Accounts - Customers Accounted for 10% or More of Trade Accounts Receivable, Net (Detail)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Accounts Receivable [Member] \| Credit Concentration Risk [Member] \| Central Banks [Member]
Concentration Risk [Line Items]
Percentage of trade accounts receivable of major customers	69.00%	69.00%

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://www.xbrl.org/2003/role/disclosureRef
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