Derivative Instruments - Designated as hedging, Financial Position (Details) - Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ (7,680)	$ (2,900)
Interest Rate Swap [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	50	430
Interest Rate Swap [Member] | Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives	(800)	(150)
Interest Rate Swap [Member] | Other long-term liabilities [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ (6,930)	$ (3,180)