Significant Accounting Policies - Comparative Data and Property and Equipment (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Accrued compensation and employee benefits	$ 6,164,000	$ 6,036,000
Property, Plant and Equipment [Line Items]
Amortization of Capitalized Software	4,000,000	3,300,000	$ 2,200,000
Impairment of Long-Lived Assets	$ 0	$ 0	$ 600,000
Property and equipment | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful lives	3 years
Property and equipment | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful lives	7 years
Software | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful lives	1 year
Software | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful lives	3 years