Acquisitions and Dispositions - Fair value of assets acquired and liabilities assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	May 26, 2017
Summary of estimated fair values of the assets acquired and liabilities assumed
Goodwill	$ 181,943	$ 184,302	$ 307,131
Ultratech
Summary of estimated fair values of the assets acquired and liabilities assumed
Short-term investments				$ 47,161
Account receivable				45,465
Inventories				59,100
Deferred cost of sales				242
Prepaid expense and other current assets				7,217
Property, plant, and equipment				18,152
Intangible assets				346,940
Other assets				6,442
Total identifiable assets acquired				530,719
Accounts payable				24,291
Accrued expenses and other current liabilities				16,356
Customer deposits and deferred revenue				4,834
Deferred income taxes				32,478
Other liabilities				11,622
Total liabilities assumed				89,581
Net identifiable assets acquired				441,138
Goodwill				192,223
Net assets acquired				633,361
Gross contractual value of accounts receivable				$ 46,000