Acquisitions - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Jul. 01, 2017
Business Acquisition [Line Items]
Goodwill	$ 101,066	$ 101,060
Advantage
Business Acquisition [Line Items]
Cash and cash equivalents			$ 2,833
Accounts receivable			14,396
Other current assets			392
Property and equipment			333
Goodwill			43,596
Other intangible assets			29,900
Total assets acquired			91,450
Accounts payable and accrued expenses			368
Accrued employee compensation and benefits			1,685
Other current liabilities			2
Total liabilities assumed			2,055
Net assets acquired			$ 89,395