Derivative Instruments (Current Period Cash Flow Hedges in AOCI (loss) before Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 4,839	$ (3,653)	$ (3,068)
Net deferred gains (losses) on cash flow hedges for the period	12,078	8,640	(680)
Amount reclassified into current period earnings	(2,070)	(148)	95
Ending Balance	$ 14,847	$ 4,839	$ (3,653)