Fair Value Measurements and Derivatives - Effects of fuel swaps dedesignated and recognized into earnings (Details 3) - Dedesignated as Hedging Instrument - Fuel Swaps - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivatives Fair Value [Line Items]
Amount reclassified from accumulated other comprehensive income (loss) into other income (expense), net	$ 2,994	$ 10,000
Loss recognized in other income (expense), net	$ (271)	$ (4,727)