Capital Stock - Schedule of Change in Treasury Shares (Detail) - shares	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Stockholders Equity Note [Abstract]
Beginning balance	10,007,327	1,808,133
Rabbi trust shares distributed/sold	(1,532)	(2,338)
Shares repurchased	0	8,200,000
Ending balance	10,005,795	10,005,795