Dividend Reinvestment Plan - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jul. 11, 2017	Jul. 20, 2012
DIVIDEND REINVESTMENT PLAN
Common shares to be issued				2,000,000	2,000,000
Minimum percentage of cash dividends	25.00%
Maximum additional cash purchase of common shares per fiscal quarter	$ 10
Percentage estimated value for dividend reinvestments	95.00%
Percentage estimated value for additional optional cash purchases	100.00%
Maximum value of common shares that may be purchased or received via transfer by participants under the dividend reinvestment plan	$ 40
Estimated value per common share	$ 19.00	$ 18.50
Purchase price per common share for dividend reinvestments	18.05	17.58
Purchase price per common share additional optional cash purchases	$ 19.00	$ 18.50
Notice period to participants	10 days
Shares issued pursuant to dividend reinvestments	342,000	325,000	331,000
Issuance of shares under optional purchase plan (in shares)	173,000	226,000	216,000