Incentive Plans - Schedule of Activity Relating to RSUs and DSUs (Parenthetical) (Detail)	6 Months Ended
Jun. 30, 2020 shares
RSUs [Member]
Share-based compensation arrangement by share-based payment award [Line Items]
Dividend participation rights	351,709

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration