Summary of Significant Accounting Policies (Narrative) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($) customer	Jun. 30, 2017 USD ($) customer	Jun. 30, 2018 USD ($) customer	Jun. 30, 2017 USD ($) customer	Dec. 31, 2017 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Fair value assets liabilities transfer between levels			$ 0
Future cash flows weighted average market yield	9.30%		9.30%		10.30%
Cash, cash equivalents, and investments, excluding restricted cash	$ 63,500,000		$ 63,500,000		$ 62,900,000
Deferred commissions	200,000		200,000
Deferred service revenue	7,500,000		7,500,000
Deferred service revenue, current	6,416,000		6,416,000		6,319,000
Deferred service revenue, non-current	1,053,000		1,053,000		$ 1,075,000
Deferred contractual revenue	4,200,000		$ 4,200,000
Service period			1 year
Restricted cash	$ 4,500,000	$ 4,500,000	$ 4,500,000	$ 4,500,000
Gene Company Limited [Member] \| Sales Revenue, Net [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of individual customers \| customer	1	1	1	1
Concentration risk, percentage	33.00%	26.00%	31.00%	28.00%
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Deferred service revenue, performance period			1 year
Deferred service revenue, non-current, recognition period			2 years
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Deferred service revenue, performance period			3 years
Deferred service revenue, non-current, recognition period			4 years