Goodwill and Other Intangible Assets - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Intangible asset amortization expense	$ 1.8	$ 1.8	$ 3.5	$ 3.8
Customer contracts and relationships
Segment Reporting Information [Line Items]
Weighted-average amortization period of intangible assets			7 years 7 months 6 days
Operating contracts and licenses
Segment Reporting Information [Line Items]
Weighted-average amortization period of intangible assets			27 years 6 months
Other
Segment Reporting Information [Line Items]
Weighted-average amortization period of intangible assets			2 years 4 months 24 days