Interest Rate Derivative Instruments (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Feb. 29, 2012	Feb. 08, 2012
Derivative [Line Items]
Unrealized gains or losses on cash flow hedge derivative effective portion		$ 0	$ 0	$ 300
Interest expense related to payments on interest rate swaps	$ 2,049	21,289	15,308
Interest Rate Swap [Member]
Derivative [Line Items]
Interest expense related to payments on interest rate swaps		0	500	$ 500
Interest Rate Swap [Member] | Fair Value Measurements, Level 2 [Member]
Derivative [Line Items]
Interest rate swap liability recorded at fair value		$ 0	$ 0
Cash Flow Hedging [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative inception date		Feb. 08, 2012
Derivative maturity date		Sep. 28, 2014
Derivative instruments, notional amount					$ 150,000	$ 150,000