Fair Value of Financial Instruments - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	$ 20,787		$ 12,260
Equity investments	202		856
Limited liability investments, at fair value	33,047		26,015
Real estate investments	10,662		10,662
Other investments	895		2,079
Short-term investments	154		152
Total assets	65,747		52,024
Subordinated debt, at fair value	50,224		50,023
Warrant liability	307
Total liabilities	50,531		50,023
U.S. government, government agencies and authorities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	15,046		5,547
States, municipalities and political subdivisions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	601		607
Mortgage-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	2,454		3,186
Corporate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	2,686		2,920
Common Stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Equity investments	179		801
Warrants
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Equity investments	23		55
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	0		0
Equity investments	195		820
Limited liability investments, at fair value	0		0
Real estate investments	0		0
Other investments	0		0
Short-term investments	0		0
Total assets	195		820
Subordinated debt, at fair value	0		0
Warrant liability	0
Total liabilities	0		0
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. government, government agencies and authorities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	0		0
Quoted Prices in Active Markets for Identical Assets (Level 1) | States, municipalities and political subdivisions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	0		0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Mortgage-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	0		0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	0		0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Common Stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Equity investments	179		801
Quoted Prices in Active Markets for Identical Assets (Level 1) | Warrants
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Equity investments	16		19
Significant Other Observable Inputs (Level 2)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	20,787		12,260
Equity investments	7		36
Limited liability investments, at fair value	6,298		206
Real estate investments	0		0
Other investments	895		2,079
Short-term investments	154		152
Total assets	28,141		14,733
Subordinated debt, at fair value	50,224		50,023
Warrant liability	0
Total liabilities	50,224		50,023
Significant Other Observable Inputs (Level 2) | U.S. government, government agencies and authorities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	15,046		5,547
Significant Other Observable Inputs (Level 2) | States, municipalities and political subdivisions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	601		607
Significant Other Observable Inputs (Level 2) | Mortgage-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	2,454		3,186
Significant Other Observable Inputs (Level 2) | Corporate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	2,686		2,920
Significant Other Observable Inputs (Level 2) | Common Stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Equity investments	0		0
Significant Other Observable Inputs (Level 2) | Warrants
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Equity investments	7		36
Significant Unobservable Inputs (Level 3)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	0		0
Equity investments	0		0
Limited liability investments, at fair value	4,635	$ 4,060	4,124	$ 2,083	$ 1,634	$ 1,397
Real estate investments	10,662	10,662	10,662	10,662	10,662	10,662
Other investments	0		0
Short-term investments	0		0
Total assets	15,297		14,786	12,745
Subordinated debt, at fair value	0		0
Warrant liability	307	$ 317	0	$ 0	$ 0	$ 0
Total liabilities	307		0
Significant Unobservable Inputs (Level 3) | U.S. government, government agencies and authorities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	0		0
Significant Unobservable Inputs (Level 3) | States, municipalities and political subdivisions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	0		0
Significant Unobservable Inputs (Level 3) | Mortgage-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	0		0
Significant Unobservable Inputs (Level 3) | Corporate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	0		0
Significant Unobservable Inputs (Level 3) | Common Stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Equity investments	0		0
Significant Unobservable Inputs (Level 3) | Warrants
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Equity investments	0		0
Measured at Net Asset Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	0		0
Equity investments	0		0
Limited liability investments, at fair value	22,114		21,685
Real estate investments	0		0
Other investments	0		0
Short-term investments	0		0
Total assets	22,114		21,685
Subordinated debt, at fair value	0		0
Warrant liability	0
Total liabilities	0		0
Measured at Net Asset Value | U.S. government, government agencies and authorities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	0		0
Measured at Net Asset Value | States, municipalities and political subdivisions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	0		0
Measured at Net Asset Value | Mortgage-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	0		0
Measured at Net Asset Value | Corporate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fixed maturity securities	0		0
Measured at Net Asset Value | Common Stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Equity investments	0		0
Measured at Net Asset Value | Warrants
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Equity investments	$ 0		$ 0