Investments (Net Realized Investment Gains (Losses)) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Gain (Loss) on Investments [Line Items]
OTTI losses	$ 0	$ 0	$ (419)	$ (10,734)
Portion of OTTI losses recognized in other comprehensive income before taxes	0	0	248	1,068
Net impairment losses recognized in earnings	0	0	(171)	(9,666)
Gross realized gains, available-for-sale securities	746	1,885	2,599	5,070
Gross realized (losses), available-for-sale securities	(1,401)	(612)	(1,468)	(5,259)
Net realized gains (losses), Short-term investments	0	18	0	18
Net realized gains (losses), trading securities	794	1,913	7,356	3,968
Net realized gains (losses), Other investments	546	447	1,719	498
Change in unrealized holding gains (losses), trading securities	(3,191)	7,115	424	7,851
Change in unrealized holding gains (losses), convertible securities, carried at fair value	285	162	598	95
Other	2	1	4	3
Total net realized investment gains (losses)	(2,219)	10,929	11,061	2,578
Corporate debt [Member]
Gain (Loss) on Investments [Line Items]
OTTI losses	0	0	(419)	(7,604)
Portion of OTTI losses recognized in other comprehensive income before taxes	0	0	248	1,068
Other investments [Member]
Gain (Loss) on Investments [Line Items]
OTTI losses	$ 0	$ 0	$ 0	(3,130)
Net impairment losses recognized in earnings				$ (3,100)

This item represents the gain (loss) realized during the period from the sale of Other Investments.

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Short-term Investment, Realized Gain (Loss)

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No definition available.

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- Definition

This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

+ References

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This item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting and losses recognized for other than temporary impairments (OTTI) of the subject investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Paragraph 9
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Amount of gain (loss) included in earnings for investments classified as other.

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The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition

Amount before tax of other than temporary impairment loss (OTTI) on investments in available-for-sale and held-to-maturity debt securities, recognized in other comprehensive loss and attributable to parent entity.

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The amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. Additionally, this item includes OTTI losses recognized during the period on investments accounted for under the cost method of accounting.

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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.

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No definition available.

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Amount of gain (loss) realized from securities classified as trading.

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Amount of unrealized holding gain (loss) recognized in the income statement for investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Amount of the unrealized gain (loss) in earnings for the period from the increase (decrease) in fair value on hybrid instruments measured at fair value.

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-Publisher FASB
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