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Fair Value Measurements - Fair Value of Cash Equivalents and Investments (Detail) - USD ($) $ in Thousands | Jun. 30, 2021 | Dec. 31, 2020
--- | --- | ---
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Mortgage loans held for sale | $ 171,450 | $ 330,758
Fair Value, Net Asset (Liability), Total | 4,552,763 | 4,048,212
Level 1 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Mortgage loans held for sale | 0 | 0
Fair Value, Net Asset (Liability), Total | 3,494,642 | 1,486,384
Level 2 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Mortgage loans held for sale | 171,450 | 330,758
Fair Value, Net Asset (Liability), Total | 1,051,708 | 2,549,486
Level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Mortgage loans held for sale | 0 | 0
Fair Value, Net Asset (Liability), Total | 6,413 | 12,342
Money market funds |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents | 3,494,642 | 1,486,384
Money market funds | Level 1 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents |  | 1,486,384
Money market funds | Level 2 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents | 0 | 0
Money market funds | Level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents | 0 | 0
U.S. government agency securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments | 829,925 | 1,037,577
U.S. government agency securities | Level 1 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments | 0 | 0
U.S. government agency securities | Level 2 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments |  | 1,037,577
U.S. government agency securities | Level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments | 0 | 0
Treasury bills |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments | 44,988 | 1,163,813
Treasury bills | Level 1 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments | 0 | 0
Treasury bills | Level 2 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments |  | 1,163,813
Treasury bills | Level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments | 0 | 0
Municipal securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents |  | 3,228
Short-term investments | 5,962 | 16,220
Municipal securities | Level 1 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents |  | 0
Short-term investments | 0 | 0
Municipal securities | Level 2 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents |  | 3,228
Short-term investments |  | 16,220
Municipal securities | Level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents |  | 0
Short-term investments | 0 | 0
Certificates of deposit |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments |  | 498
Certificates of deposit | Level 1 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments |  | 0
Certificates of deposit | Level 2 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments |  | 498
Certificates of deposit | Level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments |  | 0
IRLCs | Not Designated as Hedging Instrument |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative assets | 6,413 | 12,342
IRLCs | Level 1 | Not Designated as Hedging Instrument |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative assets | 0 | 0
IRLCs | Level 2 | Not Designated as Hedging Instrument |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative assets | 0 | 0
IRLCs | Level 3 | Not Designated as Hedging Instrument |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative assets | 6,413 | 12,342
Forward contracts | Not Designated as Hedging Instrument |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative assets | 69 |
Derivative liability | (686) | (2,608)
Forward contracts | Level 1 | Not Designated as Hedging Instrument |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative assets | 0 |
Derivative liability | 0 | 0
Forward contracts | Level 2 | Not Designated as Hedging Instrument |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative assets | 69 |
Derivative liability | (686) | (2,608)
Forward contracts | Level 3 | Not Designated as Hedging Instrument |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative assets | 0 |
Derivative liability | $ 0 | $ 0

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- Definition Fair value portion 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. + References No definition available. + Details
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- Definition Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 22 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226052-175313 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=123594938&loc=d3e13433-108611 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 + Details
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