Defined Contribution Plan	12 Months Ended
Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Defined Contribution Plan	(12) Defined Contribution Plan The Company makes available a 401(k) plan for its U.S. employees. Under the 401(k) plan, employees may make contributions which are eligible for a discretionary percentage match, in cash, as defined in the 401(k) plan and determined by the Board of Directors. The Company recognized $0.7 million, $0.4 million and $0.5 million of related compensation expense for the year ended December 31, 2018, 2017 and 2016, respectively.

The entire disclosure for an entity's employee compensation and benefit plans, including, but not limited to, postemployment and postretirement benefit plans, defined benefit pension plans, defined contribution plans, non-qualified and supplemental benefit plans, deferred compensation, share-based compensation, life insurance, severance, health care, unemployment and other benefit plans.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-URI http://asc.fasb.org/topic&trid=2228938

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 710
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-URI http://asc.fasb.org/topic&trid=2235017

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