Credit and loan agreement.

No definition available.

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- Definition

The increase in basis points to the base interest rate in the event of a default on the credit agreement.

+ References

No definition available.

+ Details

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- Definition

Line of credit facility agreement maturity date.

+ References

No definition available.

+ Details

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- Definition

Line of credit facility extended maturity date.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Line of credit facility, extension term.

+ References

No definition available.

+ Details

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- Definition

Line of credit facility maturity date.

+ References

No definition available.

+ Details

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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The stated amount of the senior unsecured credit agreement which does not include the amount by which the credit facility can be increased.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

+ Details

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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Date the debt instrument was issued, in YYYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
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- Definition

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

+ References

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Period Type:	duration

- 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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Balance Type:	credit
Period Type:	instant

- Definition

Date the credit facility first became available, in YYYY-MM-DD format.

+ References

+ Details

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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

+ Details

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Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

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- Definition

Including the current and noncurrent portions, aggregate carrying value as of the balance sheet date of loans payable (with maturities initially due after one year or beyond the operating cycle if longer).

+ References

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- Details

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Debt - Additional Information (Detail) - USD ($)						3 Months Ended	12 Months Ended
Debt - Additional Information (Detail) - USD ($)	Feb. 22, 2022	Oct. 27, 2021	Jun. 21, 2018	Mar. 23, 2018	Jun. 02, 2015	Mar. 31, 2022	Dec. 31, 2021	Sep. 12, 2019
Credit and Loan Agreement [Line Items]
Credit agreement initiation date					Jun. 02, 2015
Senior unsecured revolving credit agreement					$ 225,000,000
Term loan under credit agreement					50,000,000
Sixth Amended and Restated Prudential Agreement [Member]
Credit and Loan Agreement [Line Items]
Senior unsecured note, issuance date	Feb. 22, 2022
Sixth Amended and Restated Prudential Agreement [Member] \| Series Q Notes [Member]
Credit and Loan Agreement [Line Items]
Aggregate principal amount	$ 80,000,000
Senior unsecured note purchase agreement, maturity date	Jan. 20, 2033
Interest rate on agreement	3.65%
Sixth Amended and Restated Prudential Agreement [Member] \| Series B Notes [Member]
Credit and Loan Agreement [Line Items]
Aggregate principal amount	$ 75,000,000
Senior unsecured note purchase agreement, maturity date	Jun. 02, 2023
Interest rate on agreement	5.35%
Sixth Amended and Restated Prudential Agreement [Member] \| Series C Notes [Member]
Credit and Loan Agreement [Line Items]
Aggregate principal amount	$ 50,000,000
Senior unsecured note purchase agreement, maturity date	Feb. 25, 2025
Interest rate on agreement	4.75%
Sixth Amended and Restated Prudential Agreement [Member] \| Series D Notes [Member]
Credit and Loan Agreement [Line Items]
Aggregate principal amount	$ 50,000,000
Senior unsecured note purchase agreement, maturity date	Jun. 21, 2028
Interest rate on agreement	5.47%
Sixth Amended and Restated Prudential Agreement [Member] \| Series F Notes [Member]
Credit and Loan Agreement [Line Items]
Aggregate principal amount	$ 50,000,000
Senior unsecured note purchase agreement, maturity date	Sep. 12, 2029
Interest rate on agreement	3.52%
Sixth Amended and Restated Prudential Agreement [Member] \| Series I Notes [Member]
Credit and Loan Agreement [Line Items]
Aggregate principal amount	$ 100,000,000
Senior unsecured note purchase agreement, maturity date	Nov. 25, 2030
Interest rate on agreement	3.43%
First Amended and Restated AIG Agreement [Member] \| Series L Notes [Member]
Credit and Loan Agreement [Line Items]
Aggregate principal amount	$ 55,000,000
Senior unsecured note purchase agreement, maturity date	Feb. 22, 2032
Interest rate on agreement	3.45%
First Amended and Restated AIG Agreement [Member] \| Series G Notes [Member]
Credit and Loan Agreement [Line Items]
Aggregate principal amount	$ 50,000,000
Senior unsecured note purchase agreement, maturity date	Sep. 12, 2029
Interest rate on agreement	3.52%
First Amended and Restated AIG Agreement [Member] \| Series J Notes [Member]
Credit and Loan Agreement [Line Items]
Aggregate principal amount	$ 50,000,000
Senior unsecured note purchase agreement, maturity date	Nov. 25, 2030
Interest rate on agreement	3.43%
First Amended and Restated MassMutual Agreement [Member] \| Series M Notes [Member]
Credit and Loan Agreement [Line Items]
Aggregate principal amount	$ 20,000,000
Senior unsecured note purchase agreement, maturity date	Feb. 22, 2032
Interest rate on agreement	3.45%
First Amended and Restated MassMutual Agreement [Member] \| Series O Notes [Member]
Credit and Loan Agreement [Line Items]
Aggregate principal amount	$ 20,000,000
Senior unsecured note purchase agreement, maturity date	Jan. 20, 2033
Interest rate on agreement	3.65%
First Amended and Restated MassMutual Agreement [Member] \| Series H Notes [Member]
Credit and Loan Agreement [Line Items]
Aggregate principal amount	$ 25,000,000
Senior unsecured note purchase agreement, maturity date	Sep. 12, 2029
Interest rate on agreement	3.52%
First Amended and Restated MassMutual Agreement [Member] \| Series K Notes [Member]
Credit and Loan Agreement [Line Items]
Aggregate principal amount	$ 25,000,000
Senior unsecured note purchase agreement, maturity date	Nov. 25, 2030
Interest rate on agreement	3.43%
New York Life Agreement \| Series N Notes
Credit and Loan Agreement [Line Items]
Aggregate principal amount	$ 25,000,000
Senior unsecured note purchase agreement, maturity date	Feb. 22, 2032
Interest rate on agreement	3.45%
New York Life Agreement \| Series P Notes
Credit and Loan Agreement [Line Items]
Aggregate principal amount	$ 25,000,000
Senior unsecured note purchase agreement, maturity date	Jan. 20, 2033
Interest rate on agreement	3.65%
MetLife Agreement [Member] \| Series E Notes [Member]
Credit and Loan Agreement [Line Items]
Aggregate principal amount			$ 50,000,000
Senior unsecured note purchase agreement, maturity date			Jun. 21, 2028
Interest rate on agreement			5.47%
Fifth Amended And Restated Prudential Agreement
Credit and Loan Agreement [Line Items]
Amount of rate increase in case of default						2.00%
Revolving Facility [Member]
Credit and Loan Agreement [Line Items]
Revolving facility under credit agreement				$ 175,000,000	$ 175,000,000			$ 250,000,000
Credit facility amount				$ 250,000,000				300,000,000
Credit agreement maturity date		Mar. 31, 2022		Jun. 30, 2018
Credit agreement extended maturity date		Oct. 31, 2025		Mar. 23, 2022
Aggregate principal amount		$ 300,000,000
Line of credit facility, maturity date		Oct. 27, 2025
Line of credit facility, extension term						two six-month extensions (for a total of 12 months)
Senior unsecured note purchase agreement, maturity date						Oct. 27, 2025	Oct. 27, 2025
Revolving Facility [Member] \| Maximum [Member]
Credit and Loan Agreement [Line Items]
Aggregate principal amount		$ 300,000,000
Annual commitment fee on undrawn funds		0.25%
Revolving Facility [Member] \| Maximum [Member] \| Base Rate [Member]
Credit and Loan Agreement [Line Items]
Credit agreement margin on borrowing base rate		0.90%
Revolving Facility [Member] \| Maximum [Member] \| LIBOR [Member]
Credit and Loan Agreement [Line Items]
Credit agreement margin on borrowing base rate		1.90%
Revolving Facility [Member] \| Minimum [Member]
Credit and Loan Agreement [Line Items]
Annual commitment fee on undrawn funds		0.15%
Revolving Facility [Member] \| Minimum [Member] \| Base Rate [Member]
Credit and Loan Agreement [Line Items]
Credit agreement margin on borrowing base rate		0.30%
Revolving Facility [Member] \| Minimum [Member] \| LIBOR [Member]
Credit and Loan Agreement [Line Items]
Credit agreement margin on borrowing base rate		1.30%
Term Loan [Member]
Credit and Loan Agreement [Line Items]
Credit facility amount								$ 0
Credit agreement maturity date				Jun. 30, 2020
Credit agreement extended maturity date				Mar. 23, 2023