Preferred Stock (Schedule of Preferred Stock Activity) (Details) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Schedule of Preferred Stock Activity [Abstract]
Preferred stock, $0.01 par value, 10,000,000 shares authorized; 200,000 issued and outstanding as of June 30, 2019 and December 31, 2018	$ 176,056,000	$ 172,858,000		$ 176,056,000	$ 172,858,000	$ 174,422,000	$ 214,262,000
Redemption of Preferred Stock			$ (42,900,000)	0	(42,897,000)
Accretion on preferred stock	$ (833,000)	$ (740,000)		$ (1,634,000)	$ (1,493,000)