Debt - Additional Information (Detail)	3 Months Ended
Mar. 31, 2021 USD ($)
Senior Notes due 2022
Debt Instrument [Line Items]
Senior notes principal amount	$ 600,000,000
Senior notes interest rate	3.95%
Frequency of senior notes payment	semi-annually in arrears on March 15 and September 15
Senior notes effective interest rate	3.97%
Credit Agreement \| Revolving Credit Facility
Debt Instrument [Line Items]
Maximum loan borrowing capacity	$ 300,000,000
Increase in commitment available	300,000,000
Debt outstanding	0
Credit Agreement \| Revolving Credit Facility \| Sublimit for Issuance of Letters of Credit
Debt Instrument [Line Items]
Maximum loan borrowing capacity	100,000,000
Letters of credit outstanding	12,250,000
Repurchase Agreement \| Revolving Credit Facility
Debt Instrument [Line Items]
Maximum loan borrowing capacity	150,000,000
Borrowing base limitations	0
Debt outstanding	0
3.00% Senior Notes due 2030
Debt Instrument [Line Items]
Senior notes principal amount	$ 900,000,000
Senior notes interest rate	3.00%
Frequency of senior notes payment	semi-annually in arrears on May 15 and November 15
$600M Senior Notes Due Two Thousand Thirty
Debt Instrument [Line Items]
Senior notes principal amount	$ 600,000,000
Senior notes effective interest rate	3.02%
Additional Senior Notes Due Two Thousand Thirty
Debt Instrument [Line Items]
Senior notes principal amount	$ 300,000,000
Senior notes effective interest rate	2.00%

The Maximum Incremental Commitment amount is the sum of all incremental commitments under the repurchase facility.

No definition available.

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- Definition

Face (par) amount of debt instrument at time of issuance.

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- Definition

Description of the frequency of periodic payments (monthly, quarterly, annual).

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

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- Definition

Fair value of the amount outstanding under the credit facility.

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-Publisher FASB
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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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- Definition

Carrying value as of the balance sheet date of the outstanding short-term borrowings under a revolving line of credit used by mortgage bankers to finance the origination or purchase of loans.

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