Description of Business - Additional Information (Details)	3 Months Ended
Mar. 31, 2021
Workforce Subject to Collective Bargaining Arrangements \| Labor Force Concentration Risk
Concentration Risk [Line Items]
Percentage of workforce subject to collective bargaining agreements	79.00%

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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