Debt (Schedule of Interest Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Schedule of Interest Expense [Abstract]
Interest expense	$ 10,225	$ 9,138	$ 30,570	$ 26,486
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	695	975	2,129	2,993
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness	(350)	(26)	(350)	113
Interest Costs Capitalized Adjustment	(301)	(144)	(462)	(460)
Gain (Loss) on Extinguishment of Debt	495	0	591	0
Gains (Losses) on Restructuring of Debt	584	0	584	0
Amortization of debt issuance costs, debt discount and premium	893	873	2,668	2,613
Total interest expense	$ 12,241	$ 10,816	$ 35,730	$ 31,745