Benefit Plans (Details Textual)		1 Months Ended
	May 05, 2015 USD ($) plan_participant	May 31, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	May 06, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Current period charge	$ 5,300,000
Total benefit obligation	$ 19,600,000		$ 0	$ 0	$ 19,600,000
Number of plan participants who have not reached age 65 | plan_participant	2
Chief Executive Officer [Member]
Defined Benefit Plan Disclosure [Line Items]
Lump sum obligation at termination of plan		$ 14,400,000
Accumulated Other Comprehensive Income (Loss) [Member]
Defined Benefit Plan Disclosure [Line Items]
Current period charge	$ 2,500,000