Business Combinations - Pro Forma Information (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Release of valuation allowance on deferred tax assets		$ 48,000
Valuation allowance		55,745	$ 0	$ 0
Unrecognized tax benefits, ongoing		29,400
Revenue		1,148,214	796,607
Net loss attributable to common stockholders		(322,030)	(211,705)
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Business Acquisition [Line Items]
Acquisition related costs		40,800	13,900
Release of valuation allowance on deferred tax assets	$ 55,000	47,900
Valuation allowance			$ 53,500
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Business Acquisition [Line Items]
Acquisition related costs		$ 13,900