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Dividends on common stock: (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Nov. 05, 2025	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Dividends on common stock
Dividends declared per common share		$ 1.015	$ 0.985	$ 3.03	$ 2.925
O 2025 Q4 Dividends | Subsequent Events
Dividends on common stock
Dividends, date of approval	Nov. 05, 2025
Dividends declared per common share	$ 0.02
Dividends payable	$ 1.0
Dividends payable date	Dec. 08, 2025

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- Definition

Aggregate dividends declared during the period for each share of common stock outstanding.

+ References

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-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1

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- Definition

Date the declared dividend will be paid, in YYYY-MM-DD format.

+ References

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-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-Publisher FASB
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- Definition

Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

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-SubTopic 10
-Name Accounting Standards Codification
-Section S99
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Date the dividend to be paid was declared, in YYYY-MM-DD format.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 230
-SubTopic 10
-Section 50
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