Slicers (applies to each fact value in each table cell)

Reporting Entity [Axis]

0001280600 (http://www.sec.gov/CIK)

Income Tax Disclosure [Abstract]	Period [Axis]
	2016-01-01 - 2016-12-31
Income Tax Disclosure [Abstract]
Components of the Company's Deferred Tax Assets	The significant components of the Company's deferred tax assets are comprised of the following (in thousands):   Year Ended December 31,   2016   2015 Deferred tax assets:       U.S. and state net operating loss carryforwards $ 109,429   $ 90,732 Research and development credits 9,717   7,864 Deferred revenue 1,666   1,883 Accruals and other temporary differences 15,725   9,319 Total deferred tax assets 136,537   109,798 Less valuation allowance (136,537 )   (109,798 ) Net deferred tax assets $ —   $ —
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of income tax expense computed at the statutory federal income tax rate to income taxes as reflected in the consolidated financial statements is as follows:   Year Ended December 31,   2016   2015   2014 Federal income tax expense at statutory rate 34.0  %   34.0  %   34.0  % State income tax, net of federal benefit 5.9  %   4.6  %   4.1  % Permanent differences 4.0  %   (8.3 )%   2.0  % Research and development credit 3.1  %   1.2  %   1.6  % Other (0.1 )%   —  %   4.6  % Change in valuation allowance (46.9 )%   (31.5 )%   (46.3 )% Effective income tax rate —  %   —  %   —  %