Derivative Instruments and Hedging Activities Derivative Instruments and Hedging Activities Gain or Loss Recognized Related to Cash Flow hedges (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Derivative [Line Items]
Amount of gain (loss) related to the effective portion recognized in other comprehensive income (loss)	$ (3,533)		$ 0
Amount of gain (loss) related to the effective portion subsequently reclassified to earnings (1)	(627)	[1]	(629)	[1]
Amount of gain (loss) related to the ineffective portion and amount excluded from effectiveness testing	$ 0		$ 0

[1] (1) Consists of amounts from previous interest rate hedging programs.