Derivatives and Hedging Activities Accumulated Other Comprehensive Income Related to Derivatives (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Derivative [Line Items]
Accumulated other comprehensive income on cash flow hedges, balance at beginning of year	$ (1,123)	$ (1,923)
Net change in unrealized gain/ (loss) on cash flow hedges	(900)	(509)
Accumulated other comprehensive income on cash flow hedges, balance at end of period	$ (2,023)	$ (2,432)