Investments - Schedule of Investments in Limited Partnerships (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2017	Dec. 31, 2016
Schedule of Cost-method Investments
Other investments, cost	$ 776,054	$ 527,183
Unrealized Loss	(2,635)	(6,134)
Unrealized Gain	15,162	7,598
Other Long-term Investments
Schedule of Cost-method Investments
Total other investments	7,988
Other investments, cost	7,835	5,493
Fair value - partnerships	8,157
Other Long-term Investments	8,157	5,733
Unrealized Loss	0	(27)
Unrealized Gain	322	$ 267
Net unrealized gain (loss)	322
Limited Partnership \| Other Long-term Investments
Schedule of Cost-method Investments
Initial investment - partnerships	7,688
Other investments, cost	7,535
Fair value - partnerships	7,857
Unrealized Loss	0
Net unrealized gain (loss)	322
Limited Partnership \| Other Long-term Investments \| Level 2
Schedule of Cost-method Investments
Initial investment - partnerships	7,387
Other investments, cost	7,173
Fair value - partnerships	7,173
Unrealized Loss	0
Net unrealized gain (loss)	0
Limited Partnership \| Other Long-term Investments \| Level 3
Schedule of Cost-method Investments
Initial investment - partnerships	301
Other investments, cost	362
Fair value - partnerships	684
Unrealized Loss	0
Net unrealized gain (loss)	322
Certificates of Deposit \| Other Long-term Investments \| Level 1
Schedule of Cost-method Investments
Initial investment - certificates of deposit	300
Other investments, cost	300
Fair value - certificates of deposit	300
Unrealized Loss	0
Unrealized Gain	0
DCR Mortgage Fund VI, L.P. \| Limited Partnership \| Other Long-term Investments \| Level 3
Schedule of Cost-method Investments
Initial investment - partnerships	301
Other investments, cost	362
Fair value - partnerships	684
Unrealized Loss	0
Unrealized Gain	322
Kayne Senior Credit Fund II, L.P. \| Limited Partnership \| Other Long-term Investments \| Level 2
Schedule of Cost-method Investments
Initial investment - partnerships	1,684
Other investments, cost	1,444
Fair value - partnerships	1,444
Unrealized Loss	0
Unrealized Gain	0
DCR Mortgage Fund VII, L.P. \| Limited Partnership \| Other Long-term Investments \| Level 2
Schedule of Cost-method Investments
Initial investment - partnerships	4,000
Other investments, cost	4,056
Fair value - partnerships	4,056
Unrealized Loss	0
Unrealized Gain	0
Blackstone Alternative Solutions Trust 2015 \| Limited Partnership \| Other Long-term Investments \| Level 2
Schedule of Cost-method Investments
Initial investment - partnerships	505
Other investments, cost	475
Fair value - partnerships	475
Unrealized Loss	0
Unrealized Gain	0
Kayne Senior Credit Fund III, L.P. \| Limited Partnership \| Other Long-term Investments \| Level 2
Schedule of Cost-method Investments
Initial investment - partnerships	1,198
Other investments, cost	1,198
Fair value - partnerships	1,198
Unrealized Loss	0
Unrealized Gain	$ 0

Fair Value of Limited Partnership Interest

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

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-Publisher FASB
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Amount before tax of unrealized gain (loss) in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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A savings certificate entitling the Entity (that is, bearer) to receive interest at an established maturity date, based upon a fixed interest rate. A certificate of deposit may be issued in any denomination. Certificates of deposit are generally issued by commercial banks and, therefore, insured by the FDIC (up to the prescribed limit). Certificates of deposit generally restrict holders from withdrawing funds on demand without the incurrence of penalties. Generally, only certificates of deposit with original maturities of three months or less qualify as cash equivalents. Original maturity means original maturity to the entity holding the investment. As a related example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

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Amount, after adjustment, of cost-method investment. Adjustments include, but are not limited to, dividends received in excess of earnings after date of investment that are considered a return of investment and other than temporary impairments.

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Amount of long-term investments classified as other.

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Cash outflow related to the acquisition or continued holding of limited partnership interests held for investment purposes.

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The cash outflow from temporary investment with specific maturity and interest rate that are prohibited for current use.

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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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