Income Taxes (Details Textual) - USD ($)	3 Months Ended									12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	[1]	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax [Line Items]
Deferred Tax Assets Tax Deferred Compensation Noncurrent	$ 1,087,000				$ 1,175,000					$ 1,087,000	$ 1,175,000
Income Tax Expense (Benefit)	1,670,000	$ 1,575,000	$ 1,795,000	$ 660,000	(11,200,000)	$ 2,290,000	$ 2,272,000	$ 718,000		5,700,000	(5,920,000)	$ 8,873,000
Income Tax Examination, Penalties and Interest Accrued	$ 0				$ 0					$ 0	$ 0
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent										21.00%	35.00%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount										$ 0	$ (11,500,000)	0
Income Tax Examination, Penalties and Interest Expense										31,000	0	0
Stock Option [Member]
Income Tax [Line Items]
Income Tax Expense (Benefit)										$ 0	$ (100,000)	$ 0

[1] March 31, 2017 quarterly data have been reclassified to conform with current presentation.