Business Combinations (Preliminary Purchase Price Allocation) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	May 02, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill	$ 784,242		$ 691,712
Caisson Interventional LLC [Member]
Business Acquisition [Line Items]
Cash and cash equivalents		$ 1,468
In-process research and development		89,000
Goodwill		42,417
Other assets		918
Current liabilities		1,023
Deferred tax liabilities		16,009
Net assets acquired		$ 116,771