Retirement Benefits Plans (Details Textual) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Retirement Benefits [Abstract]
Defined contribution plan matching contribution	$ 1.5	$ 1.1	$ 3.1	$ 2.7