Consolidated funded indebtedness ratio.

No definition available.

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- Definition

Interest coverage ratio minimum.

+ References

No definition available.

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- Definition

Letter of credit maximum capacity.

+ References

No definition available.

+ Details

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- Definition

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

+ References

No definition available.

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- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 470
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-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

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Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

+ Details

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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.

+ Details

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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- Definition

Description of the payment terms of the debt instrument (for example, whether periodic payments include principal and frequency of payments) and discussion about any contingencies associated with the payment.

+ References

+ Details

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- Definition

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 470
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- Definition

Amount of unused borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance sheet date.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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+ Details

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Balance Type:	credit
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- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

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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

+ Details

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Period Type:	instant

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Description of the interest rate for the amounts borrowed under the credit facility, including the terms and the method for determining the interest rate (for example, fixed or variable, LIBOR plus a percentage, increasing rate, timing of interest rate resets, remarketing provisions).

+ 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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Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of Tier 1 risk-based capital to total leverage exposure as defined by regulatory framework.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
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Period Type:	instant

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Long-Term Debt - Additional Information (Detail)				6 Months Ended
Long-Term Debt - Additional Information (Detail)	Dec. 20, 2019	Aug. 02, 2016 USD ($)	Oct. 31, 2014	Sep. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Debt Instrument [Line Items]
Supplementary leverage ratio			4.50
Interest coverage ratio			250.00%
Borrowings outstanding under Credit Facility				$ 245,000,000	$ 560,000,000
Credit Facility, borrowings available				500,000,000.0
Letter of Credit Facility				40,000,000.0
Outstanding letters of credit , amount				5,000,000.0		$ 5,000,000.0
Debt instrument, principal amount				$ 1,260,000,000	1,575,000,000
Maturity Period 2021 [Member]
Debt Instrument [Line Items]
Unused line of credit commitment fee based on leverage ratio			0.15%
Maturity Period 2022 [Member]
Debt Instrument [Line Items]
Unused line of credit commitment fee based on leverage ratio			0.20%
Maximum [Member] \| Maturity Period 2021 [Member]
Debt Instrument [Line Items]
Unused line of credit commitment fee based on leverage ratio			0.30%
Maximum [Member] \| Maturity Period 2022 [Member]
Debt Instrument [Line Items]
Unused line of credit commitment fee based on leverage ratio			0.40%
London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member] \| Maturity Period 2021 [Member]
Debt Instrument [Line Items]
Variable margin			1.25%
London Interbank Offered Rate (LIBOR) [Member] \| Maximum [Member] \| Maturity Period 2021 [Member]
Debt Instrument [Line Items]
Variable margin			2.00%
NYFRB [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Consolidated Funded Indebtedness Ratio	1.50%
NYFRB [Member] \| Minimum [Member] \| Maturity Period 2022 [Member]
Debt Instrument [Line Items]
Variable margin			1.50%
NYFRB [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Consolidated Funded Indebtedness Ratio	2.50%
NYFRB [Member] \| Maximum [Member] \| Maturity Period 2022 [Member]
Debt Instrument [Line Items]
Variable margin			2.50%
Term Loan Agreement [Member]
Debt Instrument [Line Items]
Credit facility, interest rate description				Borrowings under the Term Loan Agreement bear interest, at our option, at a variable rate equal to either (i) the Alternate Base Rate (as defined in the Term Loan Agreement and consistent with the Revolving Credit Facility), plus an agreed spread (ranging from 50 to 150 basis points), or (ii) the Adjusted LIBO Rate (as defined in the Term Loan Agreement) plus an agreed spread (ranging from 150 to 250 basis points), which is established quarterly based on the Company's then Leverage Ratio (as defined in the Term Loan Agreement and consistent with the Revolving Credit Facility). The Company must also maintain a Leverage Ratio and Interest Coverage Ratio consistent with the Revolving Credit Facility.
Term loan facility, unused borrowing capacity, Amount				$ 665,000.0
Term loan Maturity Date				Aug. 02, 2022
Term Loan Agreement [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Variable margin	0.50%
Term Loan Agreement [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Variable margin	1.50%
4.500% Senior Unsecured Notes Due 2026 [Member]
Debt Instrument [Line Items]
Debt instrument, principal amount		$ 350,000,000.0		$ 350,000,000	$ 350,000,000
Debt instrument, interest rate		4.50%		4.50%
Interest payment period		August 2026
4.500% Senior Unsecured Notes Due 2026 [Member] \| On or After August 1, 2019 and Prior to August 1, 2021 [Member]
Debt Instrument [Line Items]
Redemption price, percentage		100.00%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit Facility, principal balance				$ 750,000,000.0
Credit Facility, available at the end				$ 665,000,000.0
Credit Facility, termination date				Aug. 02, 2022
Revolving Credit Facility [Member] \| Swingline Loan [Member]
Debt Instrument [Line Items]
Credit Facility, principal balance				$ 25,000,000.0
Line of Credit \| Maximum [Member]
Debt Instrument [Line Items]
Variable margin			0.50%
Letter of Credit [Member]
Debt Instrument [Line Items]
Unused line of credit commitment fee based on leverage ratio				0.125%