Equity - Schedule of Information with Respect to ATM Program (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2020	Jun. 30, 2019
Subsidiary Sale Of Stock [Line Items]
Net Proceeds				$ 109,321	$ 158,054
March 2019 ATM Program [Member]
Subsidiary Sale Of Stock [Line Items]
Number of Shares Sold	[1]	3,920,992	200,000	4,120,992
Net Proceeds	[1]	$ 88,939	$ 4,835	$ 93,774
December 2019 ATM Program [Member]
Subsidiary Sale Of Stock [Line Items]
Number of Shares Sold	[1]	551,200		551,200
Net Proceeds	[1]	$ 14,455		$ 14,455

[1] As of June 30, 2020, the Company had entered into forward sales transactions under the March 2019 ATM Program and December 2019 ATM Program for the sale of an additional 3,348,429 shares of its common stock that have not yet been settled. Subject to its right to elect net share settlement, the Company expects to physically settle the forward sales transactions by the maturity dates set forth in each applicable forward sale transaction placement notice, which dates range from April 2021 to June 2021. Assuming the forward sales transactions are physically settled in full utilizing a net weighted average initial forward sales price of $25.99 per share, the Company expects to receive net proceeds of approximately $87.0 million, after deducting offering costs, subject to adjustments in accordance with the applicable forward sale transaction. The Company accounted for the forward sale agreements as equity.