Segment Reporting and Foreign Operations - Assets, Depreciation, Amortization and Capital Expenditures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 1,111,811	$ 942,803	$ 778,728
Depreciation and amortization	53,582	43,755	37,425
Capital expenditures	38,623	32,837	50,959
Cardiovascular
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	1,103,806	932,927	767,952
Depreciation and amortization	52,700	42,806	36,474
Capital expenditures	38,437	32,613	50,927
Endoscopy
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	8,005	9,876	10,776
Depreciation and amortization	882	949	951
Capital expenditures	$ 186	$ 224	$ 32