Fair Value of Financial Instruments - Changes in Level 3 Liabilities (Details) - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Opening Balance	$ 13,763,000	$ 15,095,000	$ 13,647,000
Total realized and unrealized gains (losses) included in Net Income	(4,021,000)	1,332,000	(1,448,000)
Unrealized gains (losses) included in Other Comprehensive Income	0	0	0
Purchases	0	0	0
Issues	0	0	0
Sales	0	0	0
Transfers Out	(17,784,000)	0	0
Closing Balance	0	13,763,000	15,095,000
Unrealized gains (losses) for Level 3 liabilities outstanding at December 31, 2018	0	1,332,000	(1,448,000)
Contingent Consideration Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Opening Balance	13,763,000	15,095,000	13,647,000
Total realized and unrealized gains (losses) included in Net Income	(4,021,000)	1,332,000	(1,448,000)
Unrealized gains (losses) included in Other Comprehensive Income	0	0	0
Purchases	0	0	0
Issues	0	0	0
Sales	0	0	0
Transfers Out	(17,784,000)	0	0
Closing Balance	0	13,763,000	15,095,000
Unrealized gains (losses) for Level 3 liabilities outstanding at December 31, 2018	$ 0	$ 1,332,000	$ (1,448,000)

Amount of unrealized (holding) gain (loss) which is included in the statement of income (or changes in net assets) related to those liabilities still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3).

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of transfers of financial instrument classified as a liability out of level 3 of the fair value hierarchy.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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Amount of gain (loss) recognized on the income statement for financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of gain (loss) recognized in other comprehensive income (loss) for financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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Amount of issuances of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of purchases of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sales of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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