Business Combinations - Acquired Assets and Liabilities (Details) - USD ($) $ in Thousands	Feb. 28, 2020	Sep. 30, 2020	Dec. 31, 2019
Business Acquisition [Line Items]
Goodwill		$ 1,818,354	$ 1,328,045
DRG Acquisition
Business Acquisition [Line Items]
Accounts receivables	$ 52,193
Prepaid expenses	4,295
Other current assets	68,001
Computer hardware and other property	4,136
Other intangible assets	491,366
Other non-current assets	2,960
Operating lease right-of-use assets	25,099
Total assets	648,050
Accounts payable	3,474
Accrued expenses and other current liabilities	88,561
Current portion of deferred revenue	35,126
Current portion of operating lease liabilities	5,188
Deferred income taxes	47,467
Non-current portion of deferred revenue	936
Operating lease liabilities	20,341
Total liabilities	201,093
Fair value of acquired identifiable assets and liabilities	446,957
Purchase price, net of cash	944,220
Goodwill	497,263
Cash and equivalents	20,777
Database and content | DRG Acquisition
Business Acquisition [Line Items]
Other intangible assets	$ 3,966