Derivatives (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Fair value of collateral pledged to secure interest rate contracts	$ 2,017	$ 7,000
Incremental interest expense paid to interest rate swap counterparties	3,294	$ 3,321	$ 3,281
Interest Rate Swap
Derivative [Line Items]
Gain (loss) expected to be reclassified in next 12 months	(1,136)
2011 Interest Rate Swap
Derivative [Line Items]
Notional amount of interest rate derivatives	$ 93,500
Fixed rate payments, interest rate	5.50%	5.50%	5.50%
Variable rate payment rate	1.75%	1.75%	1.75%