Investments Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
Jun. 30, 2016	Dec. 31, 2015
Schedule of Investments [Line Items]
Available-for-sale equity securities	$ 134,413	$ 141,748
Gross unrealized losses	2,181	6,456
Available-for-sale securities, continuous unrealized losses, fair value	108,900	124,000
Available-for-sale securities, continuous unrealized losses, 12 months or longer, fair value	107,700	92,600
Available-for-sale securities, continuous unrealized accumulated losses, 12 months or longer	2,100	5,500
Other-than-temporary impairment on available-for-sale securities	1,600
Trading Securities	64,200	32,400
Domestic Debt Securities [Member]
Schedule of Investments [Line Items]
Trading Securities	44,600	9,000
Equity Securities [Member]
Schedule of Investments [Line Items]
Trading Securities	8,900	10,500
Mutual Fund [Member]
Schedule of Investments [Line Items]
Trading Securities	$ 8,800	$ 11,000

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

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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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