Fair Value Measurements and Fair Value of Financial Instruments (Details) - Schedule of fair value on recurring item basis - Recurring [Member] - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Assets measured at fair value	$ 423,348	$ 436,082
Municipal Securities [Member]
Assets measured at fair value	$ 9,441	$ 9,632
Valuation Techniques	Discounted cash flows	Discounted cash flows
Unobservable Input	<table cellpadding="1" cellspacing="0" style="border-collapse: collapse; font: 8.25pt Segoe UI"> <tr> <td> Discount rate</td></tr> </table>	<table cellpadding="1" cellspacing="0" style="border-collapse: collapse; font: 8.25pt Segoe UI"> <tr> <td> Discount rate</td></tr> </table>
Range	2.90%	2.90%