Fair Value of Financial Instruments - Cash and Cash Equivalents (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Cost
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and cash equivalents	$ 2,139,626	$ 1,728,692
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and cash equivalents	2,139,626	1,728,710
Cash and Overnight Deposits | Cost
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and cash equivalents	2,080,077	1,241,565
Cash and Overnight Deposits | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and cash equivalents	2,080,077	1,241,565
Corporate Commercial Paper | Cost
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and cash equivalents	0	423,261
Corporate Commercial Paper | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and cash equivalents	0	423,279
Time Deposits | Cost
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and cash equivalents	59,548	63,866
Time Deposits | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and cash equivalents	$ 59,548	$ 63,866