Common Stock (Detail) - USD ($)	3 Months Ended		11 Months Ended	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2020	Mar. 31, 2019	May 08, 2019
Class of Stock [Line Items]
Net proceeds to company	$ 3,148,000	$ 25,879,000		$ 135,215,000	$ 369,061,000
Restricted Stock/Unit Plan, and Management Incentive Plan
Class of Stock [Line Items]
Common stock issued (in shares)	72,000
Dividend Reinvestment and Stock Purchase Plan
Class of Stock [Line Items]
Common stock issued (in shares)	47,000
Common stock issued, amount	$ 3,100,000
Equity Shelf Program
Class of Stock [Line Items]
Sale of stock, maximum amount of stock allowed to be offered						300,000,000
Gross proceeds			$ 124,337,247
Agent commissions			(1,243,372)
Net proceeds to company			$ 123,093,875
Number of shares sold (in shares)			1,478,945
Weighted average price per share			$ 84.07
Sale of stock, common stock available for sale	$ 175,662,753		$ 175,662,753	$ 175,662,753