Commitments and Contingencies (Details)		1 Months Ended		3 Months Ended		6 Months Ended
	Jul. 21, 2017 lawsuit	Jul. 31, 2015 USD ($)	Jun. 30, 2014 patent	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Nov. 30, 2015
Loss Contingencies [Line Items]
Accrued legal costs				$ 910,000		$ 910,000			$ 847,000
Acquisition transaction, integration and legal costs				9,157,000	$ 500,000	9,344,000	$ 792,000
Trireme Litigation
Loss Contingencies [Line Items]
Proceeds from litigation settlement		$ 20,034,000
Accrued legal costs				0		0			$ 0
Acquisition transaction, integration and legal costs						300,000	$ 700,000
US District Court of Northern California
Loss Contingencies [Line Items]
Number of patents involved in litigation | patent			3
Shareholder Litigation
Loss Contingencies [Line Items]
Accrued legal costs				$ 0		0
Unfavorable Regulatory Action
Loss Contingencies [Line Items]
Loss contingency, loss in period						$ 8,300,000
Minimum | Scenario, Forecast | Unfavorable Regulatory Action
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss								$ 10,000,000
Maximum | Scenario, Forecast | Unfavorable Regulatory Action
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss								$ 15,000,000
Trireme
Loss Contingencies [Line Items]
Litigation liability										50.00%
AngioScore
Loss Contingencies [Line Items]
Litigation liability										50.00%
Subsequent Event | Shareholder Litigation
Loss Contingencies [Line Items]
Number of class actions lawsuits filed | lawsuit	2