Acquisition and Discontinued Operations - Income from Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss and loss adjustment expenses	$ (601)	$ (1,301)	$ (708)	$ (1,647)
Net investment income	749	1,010	1,448	1,648
Gain on change in fair value of equity investments	(556)	132	(241)	397
(Loss) gain on change in fair value of equity investments	(63)	(421)	15	744
Income from discontinued operations, net of taxes	0	594	0	980
Loss on disposal of discontinued operations, net of taxes	$ 0	(6,628)	$ 0	(6,628)
Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on disposal of discontinued operations, net of taxes					$ 1,300
Mendota and ARS | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenues		22,956		51,592
Loss and loss adjustment expenses		(18,927)		(41,728)
Commissions and premium taxes		(2,225)		(6,388)
General and administrative expenses		(3,825)		(7,778)
Net investment income		208		434
Gain on change in fair value of equity investments		(134)		(134)
(Loss) gain on change in fair value of equity investments		96		106
Other income		2,445		4,876
Total other revenue (expenses), net		(22,362)		(50,612)
Income from discontinued operations before income tax benefit		594		980
Income tax benefit		0		0
Income from discontinued operations, net of taxes		594		980
Loss on disposal of discontinued operations before income tax expense		(6,628)		(6,628)
Income tax expense		0		0
Loss on disposal of discontinued operations, net of taxes		(6,628)		(6,628)
Total loss from discontinued operations, net of taxes		$ (6,034)		$ (5,648)