Stockholders' Equity of the Company (Schedule of Common Stock Issued and Proceeds Received Dividend Reinvestments)(Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Feb. 28, 2015
Stockholders' Equity
Common stock, shares authorized	160,000,000	160,000,000
Issuance of common stock (in shares)			1,626,999
Dividend reinvestments/stock purchases under the DRSPP	$ 0	$ 124,761	$ 185,321
Dividend Reinvestment and Stock Purchase Plan (DRIP)
Stockholders' Equity
Common stock, shares authorized				3,500,000
Issuance of common stock (in shares)	2,687	775,760	608
Dividend reinvestments/stock purchases under the DRSPP	$ 277	$ 99,555	$ 64