Goodwill and Identifiable Intangible Assets, Net (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Balance at the beginning of year	$ 149,208	$ 149,208	$ 143,874
Additions (See Note 4)		52,481	5,334
Impairment adjustment	$ (1,100)	(1,105)
Balance at end of period		$ 200,584	$ 149,208
Impairment testing, Scenario one
Impairment Testing
Impairment testing, discounted cash flow analysis weightage assigned		50.00%
Impairment testing, Scenario two
Impairment Testing
Impairment testing, public company approach weightage assigned		50.00%