Acquisitions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill acquired	$ 2,604	$ 2,047
Downeast Pension Services, Inc.[Member]
Business Acquisition [Line Items]
Total consideration paid	5,700
Goodwill acquired	2,600
Contingent consideration, liability	$ 1,700
Actuarial Designs & Solutions, Inc. [Member]
Business Acquisition [Line Items]
Total consideration paid		3,000
Goodwill acquired		1,300
Columbia Ridge Capital Management, Inc. [Member]
Business Acquisition [Line Items]
Total consideration paid		1,300
Goodwill acquired		$ 800
Third Party Administrators, Inc. [Member]
Business Acquisition [Line Items]
Total consideration paid			$ 4,100
Goodwill acquired			$ 2,300