Assets and Liabilities Held for Sale and Divested Operations - Assets and Liabilities (Details) - USD ($) $ in Thousands	Oct. 01, 2020	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Goodwill		$ 1,818,354	$ 1,328,045
Derwent Product Line | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Current assets:
Accounts receivable	$ 6,774
Inventories	174
Prepaid expenses	9,010
Total current assets	15,958
Property, plant and equipment	25
Goodwill	9,129
Other intangible assets, net	10,232
Other non-current assets	602
Operating lease right-of-use assets	113
Total Assets held for sale	36,059
Current liabilities:
Accounts payable	22
Accrued expenses and other current liabilities	6,068
Current portion of deferred revenues	18,480
Current portion of operating lease liabilities	80
Total current liabilities	24,650
Non-current portion of deferred revenues	363
Operating lease liabilities	35
Total Liabilities held for sale	$ 25,048