Investments - Disaggregated Gain (Loss) on Equity Method Investments (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Fair value adjustments, net, pretax	$ 7,601	$ 16,030	$ 3,638
Equity Securities
Debt Securities, Available-for-sale [Line Items]
Fair value adjustments, net, pretax	7,601	16,208	2,945
Less: Realized (gain) loss	(19,140)	(860)	(7,964)
Unrealized gain (loss)	$ (11,539)	$ 15,348	$ (5,019)

Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

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