Goodwill and Identifiable Intangible Assets - Activity in Goodwill Balance (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Goodwill [Roll Forward]
Balance at beginning of period	$ 906,962	$ 884,185
Effect of foreign currency translation	5,208	(44,884)
Balance at end of period	$ 912,170	$ 839,301