Acquisition - Purchase Price Allocation (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Apr. 01, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Goodwill	$ 209,024		$ 130,976	$ 142,972
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