Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2025	Sep. 30, 2024
Statement of Cash Flows [Abstract]
Net cash provided by operating activities	$ 457,453	$ 432,139
Purchase of:
Fixed income securities, available-for-sale	(982,958)	(591,291)
Equity securities	(137,744)	(76,568)
Property and equipment	(3,736)	(4,187)
Other	(4,453)	(4,356)
Proceeds from sale of:
Fixed income securities, available-for-sale	383,181	80,245
Equity securities	87,874	44,863
Other	2,790	4,624
Proceeds from call or maturity of:
Fixed income securities, available-for-sale	343,319	242,955
Net proceeds from sale (purchase) of short-term investments	(90,791)	(68,373)
Net cash used in investing activities	(402,518)	(372,088)
Cash Flows from Financing Activities
Cash dividends paid	(43,146)	(38,882)
Proceeds from stock option exercises	1,042	3,041
Net cash used in financing activities	(42,104)	(35,841)
Net increase (decrease) in cash	12,831	24,210
Cash at the beginning of the period	39,790	36,424
Cash at September 30,	$ 52,621	$ 60,634

Cash inflow (outflow) from stock option exercises.

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Represents the amount of net cash outflow from other investing activities.

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Payments to Acquire Investments and Productive Assets [Abstract]

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Represents the amount of net cash inflow (outflow) from other investing activities. This element is used when there is not a more specific and appropriate element in the taxonomy.

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Proceeds from Sale of Investments and Productive Assets [Abstract]

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Amount of cash and cash equivalent, and cash and cash equivalent restricted to withdrawal or usage; attributable to continuing operation. Cash includes, but is not limited to, currency on hand, demand deposit with financial institution, and account with general characteristic of demand deposit. Cash equivalent includes, but is not limited to, short-term, highly liquid investment that is both readily convertible to known amount of cash and so near maturity that it presents insignificant risk of change in value because of change in interest rate.

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Amount of increase (decrease) in cash and cash equivalent, and cash and cash equivalent restricted to withdrawal or usage; including effect from exchange rate change and including, but not limited to, discontinued operation. Cash includes, but is not limited to, currency on hand, demand deposit with financial institution, and account with general characteristic of demand deposit. Cash equivalent includes, but is not limited to, short-term, highly liquid investment that is both readily convertible to known amount of cash and so near maturity that it presents insignificant risk of change in value because of change in interest rate.

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Amount of cash inflow (outflow) from financing activity, including, but not limited to, discontinued operation. Financing activity includes, but is not limited to, obtaining resource from owner and providing return on, and return of, their investment; borrowing money and repaying amount borrowed, or settling obligation; and obtaining and paying for other resource obtained from creditor on long-term credit.

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Amount of cash inflow (outflow) from investing activity, including, but not limited to, discontinued operation. Investing activity includes, but is not limited to, making and collecting loan, acquiring and disposing of debt and equity instruments, property, plant, and equipment, and other productive assets.

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Amount of cash inflow (outflow) from operating activity, including, but not limited to, discontinued operation. Operating activity includes, but is not limited to, transaction, adjustment, and change in value not defined as investing or financing activity.

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The net amount paid (received) by the reporting entity through acquisition or sale and maturities of short-term investments with an original maturity that is three months or less which qualify for treatment as an investing activity based on management's intention and intended by management to be liquidated, if necessary, within the current operating cycle. Includes cash flows from securities classified as trading securities that were acquired for reasons other than sale in the short-term.

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Amount of cash outflow in the form of ordinary dividends to common shareholders of the parent entity.

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Amount of cash outflow to acquire investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of cash outflow for purchase of marketable security.

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The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets.

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Amount of cash inflow from maturity, prepayment and call of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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The cash inflow associated with the aggregate amount received by the entity through sale or maturity of marketable securities (held-to-maturity or available-for-sale) during the period.

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