Common Stock and Other Equity Related Transactions - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands								9 Months Ended
	Oct. 31, 2017	Oct. 13, 2017	Sep. 25, 2017	Jul. 14, 2017	Jun. 30, 2017	Apr. 14, 2017	Mar. 31, 2017	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	May 04, 2015
Class of Stock [Line Items]
Preferred Stock Redeemed			138,400,000
Preferred stock dividends paid (usd per share)			$ 0.421875		$ 0.421875		$ 0.421875
Common stock, dividends paid (usd per share)				$ 0.4875		$ 0.4875
OP units converted to shares (shares)								1,335,247
Common Stock, Par or Stated Value Per Share (usd per share)								$ 0.01		$ 0.01
Commissions paid to sales agents								$ 723	$ 824
Subsequent Event
Class of Stock [Line Items]
Common stock, dividends paid (usd per share)		$ 0.4875
Private Placement
Class of Stock [Line Items]
Aggregate offering price											$ 125,000
Total gross proceeds								42,037	$ 50,000
Common stock, available for issuance								$ 33,000
Private Placement | Subsequent Event
Class of Stock [Line Items]
Shares of Common Stock sold (shares)	336,290
Weighted average price (usd per share)	$ 85.13
Total gross proceeds	$ 28,300
Private Placement | Common Stock
Class of Stock [Line Items]
Shares of Common Stock sold (shares)								484,913	683,548
Weighted average price (usd per share)								$ 86.69	$ 73.15
Commissions paid to sales agents								$ 526	$ 657