Summary of Significant Accounting Policies Restricted Cash (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2017
Settlement agreement installment paid	$ 1,400	$ 10,300
Cash and cash equivalents in balance sheet		46,407	$ 29,928
Restricted cash, current portion in balance sheet		4,597	55
Restricted cash, long-term			0
Total cash, cash equivalents and restricted cash in statements of cash flows		$ 51,004	$ 29,983	$ 18,260	$ 13,021
Letter of Credit
Decrease in restricted cash	$ 4,200