Revenue Recognition - Performance Obligation (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-07-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Performance obligation	$ 2,420
Expected timing of satisfaction, period	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Performance obligation	$ 3,228
Expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Performance obligation	$ 2,183
Expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Performance obligation	$ 1,623
Expected timing of satisfaction, period
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Performance obligation	$ 9,454
Product Sales [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-07-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Performance obligation	$ 664
Expected timing of satisfaction, period	6 months
Product Sales [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Performance obligation	$ 2,753
Expected timing of satisfaction, period	1 year
Product Sales [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Performance obligation	$ 2,183
Expected timing of satisfaction, period	1 year
Product Sales [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Performance obligation	$ 1,623
Expected timing of satisfaction, period
Product Sales [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Performance obligation	$ 7,223
Research and Development Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-07-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Performance obligation	$ 1,756
Expected timing of satisfaction, period	6 months
Research and Development Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Performance obligation	$ 475
Expected timing of satisfaction, period	1 year
Research and Development Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Performance obligation	$ 0
Expected timing of satisfaction, period	1 year
Research and Development Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Performance obligation	$ 0
Expected timing of satisfaction, period
Research and Development Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Performance obligation	$ 2,231