Income Taxes - Effective Income Tax Reconciliation (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
U.S. federal income tax rate									34.00%
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income (loss) before income taxes									$ (8,643,000)	$ 83,000	$ (7,220,000)
Deconsolidation of affiliate									0	55,000	0
Statutory U.S. federal income tax rate									(2,939,000)	28,000	(2,455,000)
State income taxes, net of federal benefit									(3,000)	(72,000)	(246,000)
Tax‑exempt investment income and dividend received deduction									(106,000)	(116,000)	(66,000)
Nondeductible acquisition costs and purchase adjustments									0	0	143,000
Nondeductible meals and entertainment									61,000	45,000	30,000
Valuation allowance on deferred tax assets									2,808,000	(2,050,000)	2,283,000
Net operating loss write-off									0	2,150,000	0
Other									102,000	8,000	30,000
Total income tax expense (benefit)	$ 530,000	$ 16,000	$ (623,000)	$ 0	$ 48,000	$ (48,000)	$ 48,000	$ 0	$ (77,000)	$ 48,000	$ (281,000)
Effective tax rate									0.90%	57.80%	3.90%