Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Stock-based compensation	$ 5,310	$ 4,915
Realized losses on investments	4,218	1,539
Dividend equivalents on unvested restricted stock units	1,725	1,734
Net unrealized (gains) losses on investments	(1,632)
Net unrealized (gains) losses on investments		2,512
Deferred compensation	290	78
Lease liabilities	1,205	1,452
Other	(824)	(760)
Subtotal	10,292	11,470
Less: valuation allowance	(3,201)	(4,270)
Deferred income tax asset—net	7,091	7,200
Capital Loss Carryforward	17,027	$ 6,181
Changes in Valuation Allowance	$ 1,069

Deferred Tax Assets, Dividend Equivalents on Unvested Restricted Stock Units

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible capital loss carryforwards.

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