Income Taxes (Narrative) (Details) - USD ($)	6 Months Ended	12 Months Ended
	Dec. 31, 2017	Jun. 30, 2019	Jun. 30, 2018
Income Tax Disclosure [Line Items]
Federal statutory corporate tax rate		21.00%	28.10%
Re-measurement of U.S. deferred tax assets and related valuation allowance		$ 0
Transition tax rate, cash and cash equivalents		15.50%
Transition tax rate, other than cash and cash equivalents		8.00%
Transition tax payment period		8 years
Cash payments expected to make related to Transition Tax		$ 0
Tax credit carry-forwards		$ 6,776,000	$ 7,475,000
Cumulative loss period		3 years
Unrecognized tax benefits and reserves for uncertain tax positions that would impact effective tax rate		$ 234,000	73,000
Accrued interest or penalties related to uncertain tax positions		$ 261,000
Earliest Tax Year [Member] | German Tax Authority [Member]
Income Tax Disclosure [Line Items]
Open tax year		2015
Earliest Tax Year [Member] | China Tax Authority [Member]
Income Tax Disclosure [Line Items]
Open tax year		2016
Latest Tax Year [Member] | German Tax Authority [Member]
Income Tax Disclosure [Line Items]
Open tax year		2019
Latest Tax Year [Member] | China Tax Authority [Member]
Income Tax Disclosure [Line Items]
Open tax year		2019
Internal Revenue Service (IRS) [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforward		$ 29,400,000
Operating loss carryforward related to exercise of employee stock options		8,300,000
Increase (decrease) in valuation allowance		(131,000)	$ (1,254,000)
Internal Revenue Service (IRS) [Member] | Tax Years 2021 Through 2035 [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforward		26,800,000
Internal Revenue Service (IRS) [Member] | Indefinite Period [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforward		2,600,000
Internal Revenue Service (IRS) [Member] | Tax Years 2020 Through 2034 [Member]
Income Tax Disclosure [Line Items]
Tax credit carry-forwards		$ 4,600,000
Internal Revenue Service (IRS) [Member] | Earliest Tax Year [Member]
Income Tax Disclosure [Line Items]
Open tax year		2016
Internal Revenue Service (IRS) [Member] | Latest Tax Year [Member]
Income Tax Disclosure [Line Items]
Open tax year		2019
Maximum [Member]
Income Tax Disclosure [Line Items]
Federal statutory corporate tax rate	35.00%
Maximum [Member] | Internal Revenue Service (IRS) [Member] | Tax Years 2021 Through 2035 [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforward, expiration date		Jun. 30, 2035
Maximum [Member] | Internal Revenue Service (IRS) [Member] | Tax Years 2020 Through 2034 [Member]
Income Tax Disclosure [Line Items]
Tax credit carryforward, expiration date		Jun. 30, 2034
Minimum [Member] | Internal Revenue Service (IRS) [Member] | Tax Years 2021 Through 2035 [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforward, expiration date		Jun. 30, 2021
Minimum [Member] | Internal Revenue Service (IRS) [Member] | Tax Years 2020 Through 2034 [Member]
Income Tax Disclosure [Line Items]
Tax credit carryforward, expiration date		Jun. 30, 2020