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Share Repurchase Program - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	May 06, 2021	Feb. 26, 2020
Schedule Of Share Repurchase Programs [Line Items]
Common stock repurchase program, authorized amount			$ 125,000,000	$ 50,000,000
Common stock repurchase program, number of shares repurchased	497,243	444,813
Repurchase program, approximate dollar value of shares purchased	$ 49,999,979	$ 24,999,996
Repurchase program, average price paid per share	$ 100.55	$ 56.20
February 2020 Share Repurchase Plan [Member]
Schedule Of Share Repurchase Programs [Line Items]
Common stock repurchase program, authorized remaining amount			$ 25,000,000

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Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital).

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