Fair Value Measurement Fair Value Liabilities Measured on Recurring Basis, Unobservable Inputs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	[1]
Fair Value Disclosures [Abstract]
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)	$ (7,700)
CONTINGENT EARN-OUT LIABILITY	$ 39,700	$ 47,400

[1] December 31, 2018 balances were derived from audited consolidated financial statements.