Intangible Assets Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 1997
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 23,989	$ 22,675
Net intangible assets	16,341	15,558
Amortization of Intangible Assets	530	453	$ 364
Future Amortization of Intangible Assets
2017	530
2018	530
2019	530
2020	530
2021	530
Concession Fees [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets	6,800	6,800
Accumulated amortization of intangible assets	5,236	4,964
Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets	17,189	15,875
Accumulated amortization of intangible assets	2,412	$ 2,153
Service Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets	13,360
Useful life of intangible assets				25 years
Infrastructure [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets	2,524
Contractual Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets	1,040
Other Miscellaneous Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 265
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life of intangible assets	5 years
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life of intangible assets	70 years