Subsequent Events (Details) - USD ($)	May 02, 2017	Apr. 24, 2017	Jan. 19, 2017	Apr. 26, 2017
Subsequent Event [Line Items]
Authorization to sell securities (up to)			$ 100,000,000
Subsequent event
Subsequent Event [Line Items]
Number of shares sold by selling stockholders (in shares)	9,200,000
Subsequent event | Automotive trade-in pilot program
Subsequent Event [Line Items]
Agreement term		6 months
Anticipated cash costs related to the pilot program (per quarter)		$ 1,000,000
Common stock
Subsequent Event [Line Items]
Selling stockholders may sell shares of stock (up to)			20,000,000
Common stock | Subsequent event
Subsequent Event [Line Items]
Common stock, shares authorized (up to) (in shares)				1,150,000
Price per share to sell common stock (in dollars per share)				$ 16.50
Number of shares sold in offering	1,150,000
Net proceeds from offering	$ 17,500,000
Underwriter commission and other expenses	$ 1,500,000