Stockholders' Equity (Detail)		1 Months Ended	3 Months Ended
	May 15, 2019 USD ($) sales_agent	Mar. 31, 2020 USD ($) $ / shares shares	Mar. 31, 2020 USD ($) shares	Mar. 31, 2019 USD ($)	Nov. 08, 2017 USD ($)
Class of Stock [Line Items]
Number of sales agents | sales_agent	9
Period of share repurchase program			3 years
Authorized amount for repurchase					$ 400,000,000
Repurchase of common stock (in shares) | shares		653,597
Repurchase of common stock, average price (in dollars per share) | $ / shares		$ 79.85
Payments for repurchase of common stock		$ 52,204,000	$ 52,204,000	$ 0
Remaining authorized repurchase amount		347,796,000	$ 347,796,000
At the Market Equity Distribution Agreement
Class of Stock [Line Items]
Aggregate offering price of common shares	$ 500,000,000
Shares issued (in shares) | shares			0
Value of stock available for issuance under ATM		$ 298,621,000	$ 298,621,000