Incentive Share Plan (Schedule of Nonvested and Vested Shares Activity) (Details) - 2008 Long-Term Equity Incentive Ownership Plan [Member] - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Granted, Non-Vested Shares Isused (in shares)	318,630	2,058,930	328,005	99,700	0
Shares Granted, Weighted-Average Grant Date Fair Value, Granted (in dollars per share)	$ 13.53	$ 14.40	$ 15.43	$ 13.03	$ 0.00
Shares, Vested (in shares)	(266,594)	(133,774)	(15,270)	(16,208)	(5,169)
Shares Vested, Total Vest-Date Fair Value	$ 3,829	$ 1,721	$ 224	$ 223	$ 0