Commitments and Contingencies - Series A Convertible Redeemable Preferred Stock Offering (Details) $ in Thousands			1 Months Ended	3 Months Ended	9 Months Ended
	Dec. 20, 2016 USD ($) shares	Dec. 04, 2016 USD ($) investor shares	Jan. 31, 2017 USD ($) shares	Mar. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Series A Convertible Redeemable Preferred Stock
Subsidiary, Sale of Stock [Line Items]
Adjustments to additional paid in capital, increase in carrying amount of redeemable preferred stock					$ 185,149
Total redeemable noncontrolling interests and equity					302,693	$ 332,957
Series A Convertible Redeemable Preferred Stock | Additional paid-in capital
Subsidiary, Sale of Stock [Line Items]
Adjustments to additional paid in capital, increase in carrying amount of redeemable preferred stock					185,149
Accretion to redemption value					185,149
Series A Redeemable Convertible Preferred Stock - Beneficial Conversion Feature
Subsidiary, Sale of Stock [Line Items]
Adjustments to additional paid in capital, increase in carrying amount of redeemable preferred stock					(265,368)
Series A Redeemable Convertible Preferred Stock - Beneficial Conversion Feature | Additional paid-in capital
Subsidiary, Sale of Stock [Line Items]
Beneficial conversion feature of preferred stock				$ 261,794	3,574
Adjustments to additional paid in capital, increase in carrying amount of redeemable preferred stock					$ (265,368)
Accretion period					1 year
Private Placement
Subsidiary, Sale of Stock [Line Items]
Number of investors (investor) | investor		6
Net proceeds from sale of stock	$ 328,000	$ 383,000	$ 55,000
Sale of stock, number of shares issued in transaction (in shares) | shares	343,000		57,000
Sale of stock, amount financed			$ 57,000
Sale of stock redemption period		5 years
Private Placement | Series A Convertible Redeemable Preferred Stock
Subsidiary, Sale of Stock [Line Items]
Sale of stock, number of shares agreed to be issued in transaction (in shares) | shares		400,000
Private Placement | Series A-1 Redeemable Convertible Preferred Stock
Subsidiary, Sale of Stock [Line Items]
Sale of stock, number of shares agreed to be issued in transaction (in shares) | shares		23,000
Private Placement | Series A-2 Redeemable Convertible Preferred Stock
Subsidiary, Sale of Stock [Line Items]
Sale of stock, number of shares agreed to be issued in transaction (in shares) | shares		377,000