Federal Income Taxes - Additional Information (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Deferred tax assets, additional tax basis in RCP Investments	$ 1,000,000	$ 1,700,000
Deferred tax assets, deferred interest	0	800,000
Deferred tax assets, operating loss carryforwards	$ 1,100,000	$ 1,300,000