Income Taxes (Details Textual) - USD ($)	3 Months Ended													12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	[1]	Dec. 31, 2016		Sep. 30, 2016	[1]	Jun. 30, 2016	[1]	Mar. 31, 2016	[1]	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax [Line Items]
Deferred Tax Assets Tax Deferred Compensation Noncurrent	$ 1,175,000					$ 2,723,000									$ 1,175,000	$ 2,723,000
Income Tax Expense (Benefit)	(11,200,000)	$ 2,290,000	$ 2,272,000	$ 718,000		2,208,000	[1]	$ 2,678,000		$ 2,569,000		$ 1,418,000			(5,920,000)	8,873,000	$ 6,572,000
Income Tax Examination, Penalties and Interest Accrued	$ 0					$ 0									$ 0	0	0
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent															35.00%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount															$ (11,500,000)	0	0
Scenario, Plan [Member]
Income Tax [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent														21.00%
Stock Option [Member]
Income Tax [Line Items]
Income Tax Expense (Benefit)															$ (100,000)	$ 0	$ 230,000

[1] Certain prior year amounts and March 31, 2017 quarterly data have been reclassified to conform with current presentation.