Shareholders’ Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Dividends declared per common share (in dollars per share)	$ 0.3175	$ 1.270	$ 1.225	$ 1.165
Dividends payable	$ 27,300	$ 27,300	$ 27,200
Proceeds from issuance of common shares, net		$ 76	$ 28	$ 4,402
At the Market Equity Issuance
Class of Stock [Line Items]
Issuance of common shares (in shares)				137,229
Sale of stock, price per share (in dollars per share)				$ 29.52
Proceeds from issuance of common stock, gross				$ 4,100
Proceeds from issuance of common shares, net				$ 3,800