Fair Value of Financial Instruments (Carrying Amounts and Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Assets:
Equity securities available for sale	$ 496,522	$ 376,697
Loans receivable	145,367	275,747
Fair Value
Assets:
Fixed maturity securities	12,976,680	12,462,847
Equity securities available for sale	286,652	150,866
Equity securities available for sale	496,522	376,697
Loans receivable	145,367	275,747
Cash and cash equivalents	948,710	763,631
Trading account receivables from brokers and clearing organizations	349,223	383,115
Due From Brokers, Fair Value Disclosure	0	1,713
Due from broker fair value	50,343	0
Liabilities:
Trading account securities sold but not yet purchased	120,663	37,035
Subordinated debentures	764,392	355,880
Senior notes and other debt	2,011,434	2,029,572
Carrying Value
Assets:
Fixed maturity securities	12,954,922	12,444,394
Equity securities available for sale	286,652	150,866
Equity securities available for sale	496,522	376,697
Loans receivable	142,858	273,103
Cash and cash equivalents	948,710	763,631
Trading account receivables from brokers and clearing organizations	349,223	383,115
Due From Brokers, Fair Value Disclosure	0	1,713
Due from broker fair value	50,343	0
Liabilities:
Trading account securities sold but not yet purchased	120,663	37,035
Subordinated debentures	727,242	340,320
Senior notes and other debt	$ 1,808,522	$ 1,844,621

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Fair value of subordinated debt obligations including, but not limited to, subordinated loan, subordinated bond, subordinated debenture or junior debt.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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Fair value portion of liabilities pertaining to principal and customer trading transactions, or which may be incurred with the objective of generating a profit from short-term fluctuations in price as part of an entity's market-making, hedging and proprietary trading. Examples include, but are not limited to, short positions in securities, derivatives and commodities.

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Amount of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

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Due from broker fair value

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