Subsequent Events - Convertible Promissory Notes Converted (Additional Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended
	Jul. 31, 2018	Jul. 27, 2018	Jun. 30, 2018	Jan. 18, 2018	Dec. 31, 2017	Dec. 31, 2014
Subsequent Event [Line Items]
Debt face amount			$ 1,016,277		$ 1,008,104
Interest rate percentage					8.00%
Convertible promissory notes | Convertible Promissory Notes due December 2019 and 2020, Recourse
Subsequent Event [Line Items]
Debt face amount			$ 254,120		$ 244,717
Interest rate percentage			5.00%	5.00%	8.00%	8.00%
Convertible promissory notes | Convertible Promissory Notes due December 2019 and 2020, Recourse | Subsequent Event
Subsequent Event [Line Items]
Debt face amount		$ 221,600
Interest rate percentage		8.00%
Affiliated entity | Convertible promissory notes | Convertible Promissory Notes due December 2019 and 2020, Recourse
Subsequent Event [Line Items]
Debt face amount			$ 39,900		$ 38,300
Interest rate percentage						8.00%
Convertible stock price (in dollars per share)			$ 38.64
Affiliated entity | Convertible promissory notes | Convertible Promissory Notes due December 2019 and 2020, Recourse | Subsequent Event
Subsequent Event [Line Items]
Convertible stock price (in dollars per share)		$ 38.64
Class B common stock | Subsequent Event
Subsequent Event [Line Items]
Debt conversion, shares issued (in shares)	5,734,440