Income Tax (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Income Tax [Abstract]
Income tax expense	$ 2,663	$ 2,611	$ 5,284	$ 4,568
Gross unrecognized tax benefits	$ 800		$ 800		$ 800
Mepco [Member]
Valuation Allowance [Line Items]
Valuation allowance against deferred tax assets					$ 1,100
ASU 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Tax benefit relating to compensation expense recognized		$ (300)		$ (300)