Property and Equipment (Additional Disclosures) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Depreciation expense, inclusive of expense captured in cost of revenue	$ 9,500,000	$ 7,600,000	$ 5,800,000
Impairment related to property and equipment	$ 0	$ 0	$ 0