Exchangeable Senior Notes - Summary of Amount of Interest Cost Recognized Relating to Contractual Interest Rates and Amortization of Discounts on Liability Components of Notes (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Debt Disclosure [Abstract]
Contractual interest	$ 0	$ 4,492	$ 0	$ 8,984
Amortization of discount	0	1,233	0	3,675
Total interest expense recognized	$ 0	$ 5,725	$ 0	$ 12,659