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Cash and Cash Equivalents, Short-term Investments and Restricted Cash - Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Market Value of Cash and Cash Equivalents and Available-for-Sale Investments (Detail) - USD ($) $ in Thousands | Jun. 30, 2021 | Dec. 31, 2020
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Cash and Cash Equivalents, at Carrying Value [Abstract] |  |
Cash and cash equivalents | $ 3,713,156 | $ 1,703,130
Short-term investments: |  |
Gross Unrealized Gains | 147 | 122
Gross Unrealized Losses | 0 | (59)
Restricted cash | 141,024 | 75,805
Cash, cash equivalents, short-term investments, and restricted cash, amortized cost | 4,734,908 | 3,996,980
Cash, cash equivalents, short-term investments, and restricted cash, estimated fair market value | 4,735,055 | 3,997,043
U.S. government agency securities |  |
Short-term investments: |  |
Amortized Cost | 829,791 |
Gross Unrealized Gains | 134 |
Gross Unrealized Losses | 0 |
Estimated Fair Market Value | 829,925 | 1,037,577
Treasury bills |  |
Short-term investments: |  |
Amortized Cost | 44,975 | 1,163,748
Gross Unrealized Gains | 13 | 65
Gross Unrealized Losses | 0 | 0
Estimated Fair Market Value | 44,988 | 1,163,813
U.S. government agency securities |  |
Short-term investments: |  |
Amortized Cost |  | 1,037,572
Gross Unrealized Gains |  | 57
Gross Unrealized Losses |  | (52)
Estimated Fair Market Value |  | 1,037,577
Municipal securities |  |
Short-term investments: |  |
Amortized Cost | 5,962 | 16,226
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | 0 | (6)
Estimated Fair Market Value | 5,962 | 16,220
Certificates of deposit |  |
Short-term investments: |  |
Amortized Cost |  | 498
Gross Unrealized Gains |  | 0
Gross Unrealized Losses |  | 0
Estimated Fair Market Value |  | 498
Cash |  |
Cash and Cash Equivalents, at Carrying Value [Abstract] |  |
Cash and cash equivalents | 218,514 | 213,518
Money market funds |  |
Cash and Cash Equivalents, at Carrying Value [Abstract] |  |
Cash and cash equivalents | $ 3,494,642 | 1,486,384
Municipal securities |  |
Cash and Cash Equivalents, at Carrying Value [Abstract] |  |
Cash and cash equivalents, at cost |  | 3,229
Cash and cash equivalents, gross unrealized losses |  | (1)
Cash and cash equivalents |  | $ 3,228

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- Definition Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 + Details
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- Definition Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 + Details
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454 + Details
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- Definition Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3044-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=124098289&loc=d3e6676-107765 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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- Definition Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid Investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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