Summary of Significant Accounting Policies (Topic 842 Disclosure of Impact of Adoption to Condensed Consolidated Financial Statements) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 7,364
Current portion, operating lease liabilities	1,347
Other current liabilities	185		$ 484
Operating lease liabilities, net of current portion	8,020
Other long-term liabilities	4,190		2,773
Accumulated deficit	$ (1,284,993)		(1,177,311)
As Reported [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Other current liabilities			484
Other long-term liabilities			2,773
Accumulated deficit			$ (1,177,311)
ASC 842 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Operating lease right-of-use assets		$ 5,687
Current portion, operating lease liabilities		1,510
Other current liabilities		389
Operating lease liabilities, net of current portion		6,216
Other long-term liabilities		852
Accumulated deficit		(1,177,336)
ASC 842 [Member] | Adjustment [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Operating lease right-of-use assets		5,687
Current portion, operating lease liabilities		1,510
Other current liabilities		(95)
Operating lease liabilities, net of current portion		6,216
Other long-term liabilities		(1,921)
Accumulated deficit		$ (25)