Derivatives and Hedging Activities Accumulated Other Comprehensive Income Related to Derivatives (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivative [Line Items]
Accumulated other comprehensive income on cash flow hedges, balance at beginning of year	$ (1,995)	$ (2,762)	$ (1,763)	$ (2,969)
Net change in unrealized gain/ (loss) on cash flow hedges	(463)	1,017	(695)	1,224
Accumulated other comprehensive income on cash flow hedges, balance at end of period	$ (2,458)	$ (1,745)	$ (2,458)	$ (1,745)