Notes Payable - Convertible Note Hedge and Warrant Transactions (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Notes Payable
Long-term asset	$ 171,880	$ 132,521
Long-term liability	149,458	$ 113,237
Net derivative issuance cost	21,100
Convertible Note Hedge
Notes Payable
Long-term asset	$ 91,900
Convertible Note Hedge | Class A common stock
Notes Payable
Shares issuable upon conversion of debt (in shares)	20,249,665
Initial conversion price (in dollars per share)	$ 16.58
Note Hedge Warrant Derivatives
Notes Payable
Long-term liability	$ 70,800
Note Hedge Warrant Derivatives | Class A common stock
Notes Payable
Shares into which warrants may be converted (in shares)	20,249,665
Number of trading days	150 days
Note Hedge Warrants | Class A common stock
Notes Payable
Warrants strike price (in dollars per share)	$ 21.50