Income Taxes (Schedule of Effective Income Tax Rate Reconciliation) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended		12 Months Ended
	Dec. 31, 2017	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Federal statutory income tax rate (percent)		21.00%	35.00%	28.00%
Tax at federal statutory rate (benefit)	$ (2,500)			$ (13,061)	$ 909	$ (11,209)
State income tax, net of federal benefit				521	168	75
Change in valuation allowance				25,302	3,246	9,465
Research and development credits				(7,311)	(1,355)	(1,364)
Foreign earnings taxed at other than U.S. rates				(1,065)	(492)	1,678
Stock based compensation				(5,901)	(573)	3,564
Goodwill amortization				2,004	1,795	1,672
Nondeductible officer compensation				1,927	470	77
Nondeductible meals and entertainment				510	391	289
AMT credit monetization				(155)	(155)
Deferred tax liability release - Tax reform				(2,482)
Other				(144)	(64)	89
Provision for income taxes				$ 145	$ 4,340	$ 4,336