Income Taxes (Textual) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income tax payments	$ 5,200,000	$ 400,000	$ 9,000,000
Income tax refunds	300,000	2,400,000	100,000
Discrete net tax benefit attributable to corporate tax rate reduction on existing deferred tax balances	3,100,000
Sequestration estimate on refundable alternative minimum tax credits	0
Excess executive remuneration expense disallowance estimate	0
Permanent items	800,000	800,000
Net (benefit) expense in interest and penalties related to uncertain tax positions		(700,000)	$ 200,000
Interest and penalties accrued	$ 100,000	$ 100,000