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Stock-Based Compensation - Narrative (Details) - USD ($)		1 Months Ended	7 Months Ended
	Jun. 13, 2017	Jun. 30, 2016	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
ESPP employee contributions			$ 1,419,000	$ 0
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
ESPP employee contributions			$ 1,400,000
Class A Common Stock \| Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant			5,000,000
Purchase price of common stock, percentage of fair market value	85.00%
Maximum stock purchase value, per employee			$ 12,500
Stock purchase offering period			6 months
Shares purchased during period			0
Shares distributed during period			0
Class A Common Stock \| 2014 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of additional shares authorized		3,900,000
Number of shares available for grant			1,999,415