Fair value of investment other than investment in equity security, investment in debt security and equity method investment. Includes, but is not limited to, investment in certain entities that calculate net asset value per share. Example includes, but is not limited to, investment in hedge fund, venture capital fund, private equity fund, and real estate partnership or fund.

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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 incentive obligation paid in cash or stock during the period to a limited liability corporation managing member or limited partnership general partner.

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Sum of the carrying amounts as of the balance sheet date of all investments.

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Amount of cash (inflow) outflow from investing activities classified as other.

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Amount of real estate owned for income production and capital accretion potential, not otherwise specified in the existing taxonomy. Such real estate excludes that which is occupied or used in the business, for entertainment purposes, or held in inventory for specific purposes.

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Value of investments transferred from the entity's investments in noncash transactions.

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The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of investments, not including unrealized gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity, held at each balance sheet date and included in earnings for the period.

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Fair Value of Financial Instruments Reconciliation of the fair value of recurring Level 3 fair value measurements (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Payments for (Proceeds from) Other Investing Activities			$ (119)	$ 521
Loss on change in fair value of limited liability investment			(1,592)	789
Alternative Investment	$ 31,564		31,564			$ 32,211
Real estate investments, at fair value (cost $10,225 and $10,225, respectively)	10,662	$ 10,662	10,662	10,662	$ 10,662	10,662	$ 10,662	$ 10,662
Transfer from Investments	0	0	0	0
Investments	68,277		68,277			79,839
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Payments for (Proceeds from) Other Investing Activities	307	560	1,285	664
Incentive Distribution, Distribution	(34)	0	(345)	(86)
Loss on change in fair value of limited liability investment	(26)	16	(7)	(14)
Alternative Investment	2,330	1,503	2,330	1,503	$ 2,083	1,397	$ 927	$ 939
Real estate investments, at fair value (cost $10,225 and $10,225, respectively)	10,662		10,662			10,662
Investments	12,992		12,992			$ 12,059
Fair Value, Inputs, Level 3 [Member] \| Other than Securities Investment [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investments	$ 12,992	$ 12,165	$ 12,992	$ 12,165