Stockholders' Equity (Detail)			9 Months Ended
	Aug. 09, 2021 USD ($) sales_agent	Mar. 23, 2021 USD ($) $ / shares shares	Sep. 30, 2021 USD ($) shares	Oct. 15, 2020 USD ($)
Class of Stock [Line Items]
Number of sales agents | sales_agent	10
Shares issued (in shares) | shares		1,600,000
Net proceeds		$ 206,573,000
Average sales price (in dollars per share) | $ / shares		$ 129.13
Share repurchase program, authorized amount				$ 400,000,000
Repurchase of common stock (in shares) | shares			0
At the Market Equity Distribution Agreement
Class of Stock [Line Items]
Aggregate offering price of common shares	$ 800,000,000
Shares issued (in shares) | shares			585,685
Net proceeds			$ 66,786,000