Segment and Geographic Information (Revenue By Product Type) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue from External Customer [Line Items]
Revenue	$ 57,725	$ 54,757	$ 40,824	$ 53,225	$ 61,321	$ 56,614	$ 58,906	$ 53,966	$ 206,531	$ 230,807	$ 201,630
United States [Member]
Revenue from External Customer [Line Items]
Revenue									169,244	185,829	162,146
United States [Member] | Open Ablation [Member]
Revenue from External Customer [Line Items]
Revenue									75,399	80,205	72,250
United States [Member] | Minimally Invasive Ablation [Member]
Revenue from External Customer [Line Items]
Revenue									25,647	34,842	35,053
United States [Member] | Appendage Management [Member]
Revenue from External Customer [Line Items]
Revenue									66,981	68,166	52,891
United States [Member] | Ablation And Appendage Management [Member]
Revenue from External Customer [Line Items]
Revenue									168,027	183,213	160,194
United States [Member] | Valve Tools [Member]
Revenue from External Customer [Line Items]
Revenue									1,217	2,616	1,952
International [Member]
Revenue from External Customer [Line Items]
Revenue									37,287	44,978	39,484
International [Member] | Open Ablation [Member]
Revenue from External Customer [Line Items]
Revenue									18,655	24,945	21,118
International [Member] | Minimally Invasive Ablation [Member]
Revenue from External Customer [Line Items]
Revenue									6,171	8,349	9,176
International [Member] | Appendage Management [Member]
Revenue from External Customer [Line Items]
Revenue									12,353	11,476	8,988
International [Member] | Ablation And Appendage Management [Member]
Revenue from External Customer [Line Items]
Revenue									37,179	44,770	39,282
International [Member] | Valve Tools [Member]
Revenue from External Customer [Line Items]
Revenue									$ 108	$ 208	$ 202