Acquisitions - Manatee Works Inc. Purchase Price Allocation (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Aug. 21, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill	$ 95,280	$ 81,448		$ 77,388
Manatee Works, Inc. [Member]
Business Acquisition [Line Items]
Prepaid expenses and other current assets			$ 23
Goodwill			4,060
Purchase price			4,813
Customer Relationships [Member] | Manatee Works, Inc. [Member]
Business Acquisition [Line Items]
Finite-lived intangible assets			140
Technology-Based Intangible Assets [Member] | Manatee Works, Inc. [Member]
Business Acquisition [Line Items]
Finite-lived intangible assets			$ 590