Exchangeable Senior Notes - Repurchase of Debt (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Total consideration paid for repurchase	$ 2,014,730	$ 1,977,805	$ 1,109,854
Exchangeable Senior Notes
Debt Instrument [Line Items]
Principal amount repurchased	575,000	0	49,259
Extinguishment of liability component	575,000	0	49,019
Reacquisition of equity component	0	0	31,251
Total consideration paid for repurchase	575,000	0	80,270
Extinguishment of liability component	(575,000)	0	(49,019)
Discount on exchangeable senior notes	0	0	(230)
Related debt issuance costs	0	0	(10)
Gain/(loss) on repurchase	$ 0	$ 0	$ 0