Fair value measurements (Tables)

6 Months Ended

Jun. 30, 2018

Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]

Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis

The fair value of the Company’s financial assets and liabilities measured on a recurring basis were as follows:

	June 30, 2018											December 31, 2017
(U.S. Dollars, in thousands)	Level 1		Level 2			Level 3			Total			Total
Assets
Collective trust funds	$	—	$	100		$	—		$	100		$	100
Treasury securities		558		—			—			558			556
Equity warrants		—		289			—			289			311
Equity securities		—		4,379			—			4,379			2,457
Debt security		—		—			18,010			18,010			16,050
Total	$	558	$	4,768		$	18,010		$	23,336		$	19,474
Liabilities
Contingent consideration	$	—	$	—		$	(26,600	)	$	(26,600	)	$	—
Deferred compensation plan		—		(1,369	)		—			(1,369	)		(1,379	)
Total	$	—	$	(1,369	)	$	(26,600	)	$	(27,969	)	$	(1,379	)

Schedule of Reconciliation For Contingent Consideration Measured At Fair Value Using Significant Unobservable Inputs

The following table provides a reconciliation of the beginning and ending balances for the contingent consideration measured at fair value using significant unobservable inputs (Level 3):

(U.S. Dollars, in thousands)	2018
Contingent consideration at January 1	$	—
Acquisition date fair value		25,491
Increase in fair value recognized in other income (expense)		1,109
Contingent consideration at June 30	$	26,600

Fair Value, Inputs, Level 3 [Member]

Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]

Schedule of Reconciliation of Available for Sale Debt Securities

The following table provides a reconciliation of the beginning and ending balances for debt securities measured at fair value using significant unobservable inputs (Level 3):

(U.S. Dollars, in thousands)	2018		2017
Debt security at January 1	$	16,050	$	12,220
Accrued interest income		—		—
Gains or losses recorded for the period
Recognized in net income		—		(5,585	)
Recognized in other comprehensive income		1,960		2,365
Debt security at June 30	$	18,010	$	9,000