Stock Compensation Plans (Schedule of Restricted Stock Units) (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested grants, beginning balance	733,000	606,500	1,042,000
Granted	1,211,500	414,000	2,000
Vested	(990,500)	(271,500)	(410,500)
Forfeited	(9,500)	(16,000)	(27,000)
Non-vested grants, ending balance	944,500	733,000	606,500
Weighted average share price, granted	$ 7.98	$ 6.84	$ 11.52
Weighted average share price, vested	$ 7.22	$ 8.72	$ 7.42