Borrowings - Total Long Term Borrowings (Details)				1 Months Ended
	Apr. 18, 2017 USD ($)	Feb. 23, 2015 USD ($) SecurityLoan	Sep. 11, 2014 USD ($)	Oct. 31, 2017 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)		Sep. 18, 2014 USD ($)
Long term borrowings
Long term borrowings					$ 3,489,000	$ 26,564,000	[1]
Construction Line of Credit for Main Campus Construction | Line of Credit
Long term borrowings
Long term borrowings					0	22,990,000
Line of credit, maximum borrowing capacity			$ 24,000,000
Debt instrument, fixed interest rate			3.95%
Debt instrument term			84 months
Line of credit facility, periodic payment			$ 146,000
Related Party Loans Transfered to Unaffiliated Commercial Bank | Notes Payable to Banks
Long term borrowings
Long term borrowings					$ 3,471,000	3,574,000
Debt instrument term		60 months
Number of related party loans transferred | SecurityLoan		2
Debt instrument, face amount		$ 4,700,000.0
Debt instrument, interest rate effective percentage					5.50%
Collateral amount					$ 3,500,000
Related Party Loans Transfered to Unaffiliated Commercial Bank | Notes Payable to Banks | Prime Rate
Long term borrowings
Basis spread on variable rate		(1.00%)
Note Payable Revolving Line of Credit with a Unaffiliated Commercial Bank | Notes Payable to Banks
Long term borrowings
Long term borrowings					0	0
Line of credit, maximum borrowing capacity	$ 25,000,000							$ 8,100,000.0
Debt instrument term	24 months
Remaining available credit facility					25,000,000
Note Payable Revolving Line of Credit with a Unaffiliated Commercial Bank | Notes Payable to Banks | Prime Rate
Long term borrowings
Basis spread on variable rate	0.50%
Capital Lease with Unaffiliated Lease Company | Capital Lease Obligations
Long term borrowings
Capital lease obligation					$ 18,000	$ 0
Capital lease obligations, noncurrent				$ 19,000
Term of contract				60 months
Option to purchase equipment, amount				$ 1.00

[1] Derived from audited consolidated financial statements.