Acquisition - Purchase Price Allocation (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Apr. 01, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill	$ 208,186	$ 209,024		$ 130,976
Cogent Partners, LP
Business Acquisition [Line Items]
Current assets			$ 13,970
Property and equipment			599
Other assets			651
Identifiable intangible assets			1,300
Goodwill			93,116
Total assets			109,636
Current liabilities			9,640
Total liabilities			9,640
Net assets			$ 99,996