Description of Business and Summary of Significant Accounting Policies (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Assets [Abstract]
Total assets measured at fair value	[1]	$ 33,010	$ 28,571
Liabilities [Abstract]
Total liabilities measured at fair value	[1]	29,285	37,096
Fair Value, Inputs, Level 1 [Member]
Assets [Abstract]
Total assets measured at fair value	[1]	33,010	28,571
Fair Value, Inputs, Level 2 [Member]
Liabilities [Abstract]
Total liabilities measured at fair value	[1]	0	0
Fair Value, Inputs, Level 3 [Member]
Liabilities [Abstract]
Total liabilities measured at fair value	[1]	29,285	37,096
Contingent accrued earn-out acquisition consideration [Member]
Liabilities [Abstract]
Derivative liabilities	[1],[2]	29,285	37,096
Contingent accrued earn-out acquisition consideration [Member] | Fair Value, Inputs, Level 3 [Member]
Liabilities [Abstract]
Derivative liabilities	[1],[2]	29,285	37,096
Certificates of Deposit [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities		23,342	22,293
Certificates of Deposit [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities		23,342	22,293
Mutual Fund [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities		9,668	6,278
Mutual Fund [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities		9,668	6,278
Certificates of Deposit [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities		2,860	2,190
Mutual Fund [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities		$ 9,668	$ 785

[1] months ended September 30, 2018 and the year ended December 31, 2017 there were no transfers between fair value levels 1, 2, or 3.

[2] The income valuation approach is applied and the valuation inputs include the contingent payment arrangement terms, projected cash flows, rate of return, and probability assessments.