Earnings Per Share (Narrative) (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share Narrative [Line Items]
Weighted average unvested shares outstanding	200,000	200,000	200,000
Anti-dilutive stock options excluded from dilutive earnings per share calculation	682	0	0
5.417% Series 1 Cumulative Convertible Preferred Shares
Earnings Per Share Narrative [Line Items]
Cumulative convertible preferred share, dividend rate	5.417%	5.417%	5.417%