Stockholders' Equity - Narrative (Detail) - USD ($)	1 Months Ended	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock in public offering of common stock (in shares)	2,985,575
Issuance of common stock in public offering of common stock	$ 1,213,400,000	$ 101,791,000	$ 1,213,434,000
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units, approved (in shares)		653,281
Weighted-average grant date fair value (in dollars per share)		$ 579.24
Service period (in years)		3 years 3 months 21 days
2018 ATM Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock in public offering of common stock (in shares)		162,530
Issuance of common stock in public offering of common stock		$ 101,800,000
Sale of stock, equity offering agreement, authorized				$ 750,000,000.0