Subsequent Events (Details)				12 Months Ended
	May 01, 2018 USD ($) ft²	Mar. 01, 2018 USD ($) ft²	Jan. 09, 2018 USD ($) shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Subsequent Event [Line Items]
Treasury stock repurchased				$ 112,910	$ 431,755
Subsequent Event | Principle Executive Office Lease | San Antonio, TX | Forecast
Subsequent Event [Line Items]
Lessee, operating lease, term of contract	76 months
Subsequent Event | Principle Executive Office Lease | San Antonio, TX | Forecast | Minimum
Subsequent Event [Line Items]
Area of leased property | ft²	6,000
Operating leases, annual rent expense	$ 117,000
Subsequent Event | Principle Executive Office Lease | San Antonio, TX | Forecast | Maximum
Subsequent Event [Line Items]
Area of leased property | ft²	10,535
Operating leases, annual rent expense	$ 232,000
Subsequent Event | Sales Offices And Operations Consolidation | Nashville, TN | Forecast
Subsequent Event [Line Items]
Lessee, operating lease, term of contract		62 months
Area of leased property | ft²		3,794
Subsequent Event | Sales Offices And Operations Consolidation | Nashville, TN | Forecast | Minimum
Subsequent Event [Line Items]
Operating leases, annual rent expense		$ 109,000
Subsequent Event | Sales Offices And Operations Consolidation | Nashville, TN | Forecast | Maximum
Subsequent Event [Line Items]
Operating leases, annual rent expense		$ 122,000
Subsequent Event | Officers, Employees And Directors
Subsequent Event [Line Items]
Treasury stock repurchased (in shares) | shares			397,845
Treasury stock repurchased			$ 956,128
Subsequent Event | Share Buyback Plan
Subsequent Event [Line Items]
Additional authorized amount			2,000,000
Authorized amount			3,000,000
Remaining authorized repurchase amount			$ 2,455,030