Derivative and Hedging Activities Derivative and Hedging Activities - Gain Loss in AOCI (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other Nonoperating Income (Expense) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains recognized in income on derivatives (ineffectiveness portion and amount excluded from effectiveness testing)	$ 18
Other Nonoperating Income (Expense) [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recorded in other expense, net	(72)	596	(437)
Other Comprehensive Income (Loss) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains in Accumulated OCI on derivatives (effective portion)	$ 311