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Investments (Unrealized Gains on Investments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Proceeds from Sale of Equity Securities	$ 137,294	$ 113,339	$ 37,960
Net unrealized gains	215,688	2,391	124,679
Deferred income tax expense	(45,294)	(502)	(44,103)
Net unrealized gains, net of deferred income tax	170,394	1,889	80,576
Cumulative effect adjustment			(25,000)
Increase (decrease) in net unrealized gains in OCI, net of deferred income tax	168,505	(65,881)	38,453
Equity Securities [Member]
Net unrealized gains	0	0	38,894
Available-for-sale Securities [Member]
Net unrealized gains	215,634	2,302	85,806
AFS Fixed Income Securities [Member]
Net unrealized gains			124,700
Total HTM Securities [Member]
Net unrealized gains	31	89	(21)
Short-term Investments [Member]
Net unrealized gains	23	0	0
Accounting Standards Update 2018-02 [Member] | Investments [Member]
Cumulative effect adjustment	0	(17,920)	0
Accounting Standards Update 2018-02 [Member] | Retained Earnings [Member]
Cumulative effect adjustment		0	(5,707)	$ 0
Accounting Standards Update 2018-02 [Member] | Retained Earnings [Member] | Investments [Member]
Cumulative effect adjustment		(17,900)
Accounting Standards Update 2016-01 [Member]
Cumulative effect adjustment	$ 0	30,726	0
Accounting Standards Update 2016-01 [Member] | Retained Earnings [Member]
Cumulative effect adjustment		$ 0	$ 30,726	$ 0

X

- Definition

Tax effect of unrealized gain (loss) on investments in accumulated other comprehensive income.

+ References

No definition available.

+ Details

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- Definition

This item represents the net unrealized gains (losses) on investments in other comprehensive income, net of deferred income tax.

+ References

No definition available.

+ Details

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- Definition

The cash inflow associated with the sale of equity securities.

+ References

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- Definition

Total change in unrealized gains/losses on investment securities net of tax.

+ References

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- Definition

This item represents the net unrealized gains (losses) on investments in other comprehensive income.

+ References

No definition available.

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- Definition

Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

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No definition available.

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